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Biomedical subjects

S Xu

Publications and source records attributed to S Xu.

At least 523 records · Page 29Linked to original sources
PubMed1991

Cytogenetic studies on a human rectal carcinoma cell line (HR-8348).

Cytogenetic properties of a human rectal carcinoma cell line (HR-8348) established in China are described. The early (29th passage) and late (93rd passage) passage cells were used for chromosome analysis. HR-8348 was found to have an essentially triploid karyotype. This distribution of chromosome numbers was rather dispersed in early passage, whereas it was concentrated in the 65-70 range in late passage. G-banded karyotype analysis also showed that the numerical distribution of chromosomes was dispersed in early passage and was associated with more abnormal chromosomes. In late passage, the numerical distribution became more stable and the number of abnormal chromosomes was reduced. In 60 metaphases analyzed, 10 marker chromosomes were found. The frequencies of M1, M2 and M3 were 100% in both early and late passage cells. The morphological characteristics of these marker chromosomes and their possible origin and role in the pathogenesis of colorectal carcinoma are discussed.

Chromosome Aberrations↗
PubMed1991

[Autologous mixed lymphoma reaction in patients with malignant lymphoma].

Human T cells can be induced to proliferate in vitro when they are cocultured with autologous Non-T cells. This phenomenon has been termed the autologous mixed lymphocyte reaction, AMLR. In this study, AMLR was assessed in 14 untreated patients with lymphoma and 13 age-and-sex-matched healthy controls. This difference was significant (P less than 0.001), suggesting that patients with lymphoma may have impaired AMLR.

Adolescent↗
PubMed1991

[Invasiveness and metastasis of tumor spheroid aggregates of human giant cell carcinoma (lung clone strain PLA801-95D) in vitro and in vivo].

Invasion modols of tumor spheroid aggregates in vitro and in vivo were established by using human giant cell carcinoma (lung strain PLA801-95D). PLA801-95D cells from monolayer cultures were suspended and allowed to form spheroid aggregates for 3 d on a gyratory shaker. In organ culture, PLA801-95D (0.2 mm in diameter) were confronted with 0.4 mm round precultured heart fragments (PHF), then co-cultured on a gyratory shaker. PLA801-95D cells showed a strong capacity of invasion in vitro. In vivo, PLA801-95D spheroids (0.3 mm in diameter) were transplanted subcutaneously into the auricles and flanks of BALB/c nude mice. No s. c. tumor growth was noted in the auricle 4 months after transplantation, but at the s. c. flank, tumors were found in 3 of 5 mice, with invasive growth seen at the site of transplantation. Metastases were found in regional drainage lymph nodes (axillary, submaxillary and inguinal lymph nodes) and in the lungs. PLA801-95D cells had high malignancy in vitro and in vivo. Both spheroid invasion models proved to be suitable for judging the malignancy of human tumor cells and for studying the mechanism of human tumor invasion.

Animals↗
PubMed1991

[Studies on the antitumor antibiotic aclacinomycin A].

During the course of screening for new antitumor antibiotics, a new anthracycline antibiotic--aclacinomycin A was separated from the broth and mycelium of Streptomyces AC-57. The strain AC-57 was isolated from the soil collected in the Shanghai suburbs. According to its culture and physiological characteristics the producer was identified as Str. galilaeus AC-57. The broth and mycelium were extracted and treated with solvents as usual way. The aclacinomycin A was separated by silica-gel column chromatography eluted with chrolo-form-methanol. Aclacinomycin A, its aglycone and sugar components were identified by comparison of their physico-chemical and spectral data (MS, UV, IR, 1H-NMR, and 13C-NMR) with authentic compound, purified from the market sample.

Aclarubicin↗
PubMed1990

[The evaluation of thyroid suppression test in predicting the outcome of Graves' disease treated by short-term antithyroid drugs].

One hundred and fifteen new patients with Graves' hyperthyroidism were received thyroid suppression test after cessation of 6 month course of drug therapy. The results of follow up for another 12 months were that one of them had lost, 48 cases were in remission, and 66 cases had relapsed. The present study shows that thyroid suppression test, including the 4th, 6th and 24th hour suppression rates, is useful in predicting the outcome of drug therapy. The effect of 6th hour suppression rate is better than that of 24th and 4th hours, with 75.8% sensitivity, 75.0% specificity and 75.4% accuracy when 30% of thyroid suppression rate is as out-off point which is decided by ROC curve. It is suggested that 6 hour 30% suppression rate is better than the traditional 24 hour 50% suppression rate in the prediction of outcome of drug therapy.

Adult↗
PubMed1990

Studies on medicamentous inhibitory therapy for esophageal precancerous lesions--3- and 5-year inhibitory effects of antitumor-B, retinamide and riboflavin.

Since 1983, we have been conducting inhibitory therapy for precancerous lesions of the esophagus in two regions of Henan Province considered high-risk areas of esophageal carcinoma. Our goal was to effect a 50% reduction in the canceration rate of marked esophageal dysplasia. By means of a cytological survey, 2531 cases of marked esophageal dysplasia and 3393 cases of mild esophageal dysplasia were selected. The former were randomly divided into 3 groups for antitumor-B (ATB, a mixture of Chinese herbs), retinamide (4-ethoxycarbophenylretinamide) and placebo treatment respectively, and the latter into 2 groups treated with riboflavin and placebo respectively. Treatment was continued for 3 or 5 years (administration rate greater than 90% in all groups) and esophageal cytology reexamined (reexamination rates were 94.1% and 92.5% respectively). Our results were as follows: 1) ATB 3- and 5-year subjects saw the canceration rate of marked esophageal dysplasia drop by 52.2% and 47.3% respectively as compared to control (P less than 0.01). 2) Retinamide lowered the canceration rate by 37.3% after a 3-year treatment period, with this reduction reaching 43.2% after an additional 2 years of treatment with increased dosages (P less than 0.05, P less than 0.01). 3) In the riboflavin group, the canceration rate of mild esophageal dysplasia was reduced by 22.2% and 34.8% after 3 and 5 years of treatment respectively, but these differences were not statistically significant. The above results verify the efficacy of medicamentous inhibitory therapy for esophageal precancerous lesions.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

[Effects of promethazine on acupuncture analgesia].

Promethazine, one of histaminergic H1-receptor antagonist, was often used as an adjuvant drug prior to and during acupuncture anesthesia in clinics, However, its effects was not known clearly. By using potassium iontophoretic dolorimetry and stimulating unilateral "Hegu" and "Waiguan" points with electroacupuncture (EA) in 42 rabbits, we found that Promethazine could drop the pain threshold in small dosages (0.5 mg/kg, 1 mg/kg) and raise the pain threshold in relatively large dosages (2 mg/kg, 4 mg/kg). In different dosages (1 mg/kg, 2 mg/kg), promethazine could attenuate the analgesic effect of EA. It was suggested that promethazine should be used carefully in acupuncture anaesthesia.

Acupuncture Analgesia↗
PubMed1990

[Enhancing effect of chuangxinmycin on synthesis of enzymes in tryptophan synthesis pathway of chuangxinmycin-resistant mutant strain of E. coli].

Chuangxinmycin (CXM) and L-trp cause repression of trp-operon in wild strain of E. coli and indolepropanic acid (IPA) causes derepression of this strain. In CXM-resistant mutant strain, CXM and IPA both cause derepression, and interaction of CXM and IPA is competitive. However, L-trp results in neither repression nor derepression in the mutant, but it can counteract the activity of CXM or IPA. These results suggest that there are repression and derepression sites on repressor of E. coli. CXM can bind to both sites, but mainly to repression site. The structure of repression site of the CXM-resistant mutant is altered, so that CXM can not bind to the repression site and binds mainly to the derepression site, thus leading to the derepression of trp-operon.

Anthranilate Synthase↗
PubMed1990

[A preliminary study of the inhibiting mechanism of anisodamine on rabbit platelets activated by E. coli endotoxin].

Bacterial endotoxin binds to platelets and causes platelet aggregation, thrombocytopenia, increase in thromboxane A2 production, serotonin release and increase in the generation of platelet factor 3 procoagulant activity. These effects have been demonstrated in a variety of animal species. Much evidence has shown that such changes may participate in the pathogenesis of DIC and RDS in septic shock. The anisodamine (654) antishock effect has been studied from different angles for more than 20 years, with its effect on the cardiovascular system, including the microcirculation, being demonstrated. But few reports concerning its effect on platelet function have emerged. In this study, the effect of anisodamine on rabbit platelet aggregation, release, morphological changes, cellular cAMP, and membrane lipid fluidity induced by E. coli endotoxin were studied both in vivo and in vitro. After anisodamine intervention, all of these parameters improved to a certain extent. The possible protective mechanisms of anisodamine on platelets both in vivo and in vitro are discussed.

Animals↗
PubMed1990

Cumulative effect of repeated ischemia on brain edema in the gerbil. Biochemical and physiological correlates of repeated ischemic insults.

Using a bilateral carotid artery occlusion model in the gerbil, we evaluated the cumulative effect of repeated ischemic insults on various physiological and biochemical parameters in brain. The most striking consequence of repeated occlusions is a profound, delayed increase in brain edema between 6- and 24-hr recirculation, after a series of three 5-min occlusions carried out at 1-hr intervals. This increment in brain water is accompanied by morphological evidence of compressed capillaries with increased filling of larger vessels, consistent with impaired microcirculation even though total blood flow and total vascular volume return toward control levels. The effect on edema is most severe when occlusions are repeated during the period of postischemic hypoperfusion, although the mechanisms responsible for this effect remain to be determined. Histograms of cerebral cortical oxygen tension show a shift toward progressively lower values during the recirculation interval after each occlusion, suggesting that secondary hypoxia accompanying hypoperfusion may worsen the impact of successive ischemic intervals. Although levels of PCr and ATP indicate adequate recovery of energy metabolism between occlusions, slight elevations of brain lactate persist, consistent with continued hypoxia. Under the conditions employed in these studies, repeated occlusions give rise to progressively more prolonged deficits in brain protein synthesis activity, which may thus provide a useful index of the severity of the accumulated ischemic insult. Continued studies using this well-defined model should provide further insight into the pathophysiology of ischemic brain edema.

Animals↗
PubMed1989

Decrease of anion selectivity caused by mutation of Thr501 and Gly502 to Glu in the hydrophobic domain of the colicin E1 channel.

Structure-function relations of the colicin E1 ion channel were studied through the effects of mutations in the 35-residue hydrophobic region of the channel polypeptide and neighboring residues in the channel domain. Mutation of neutral residues threonine 501 and glycine 502 to a more polar or charged glutamic acid generated a protein whose channel conductance properties in each case had a decreased selectivity for anions. There was no significant effect on ion selectivity caused by mutations that changed residue charge outside the hydrophobic domain at the neighboring aspartic acid 509 or at glycine 439. The Thr501----Glu and Gly502----Glu mutants possessed lower cytotoxic and in vitro activity. An altered thermolysin cleavage pattern and a greater binding to membrane vesicles at pH greater than 4.5 of the Gly502----Glu mutant indicated greater exposure of its COOH-terminal hydrophobic domain in solution. It is concluded that the hydrophobic nature of threonine 501 and glycine 502 is important in the structure of the channel lumen and the soluble colicin. Altering proline 462, a residue conserved in five sequenced channel-forming colicins, had no significant effect on channel properties. These conclusions are discussed in the context of sequence-structure-function concepts for channel proteins.

Amino Acid Sequence↗
PubMed1989

[Etiological diagnosis of cryptosporidiosis].

1,014 faecal specimens were collected from 4 hospitals in Nanjing to investigate the infection of Cryptosporidium. Each faecal specimen was smeared and screened by auramine phenol staining method for oocyst, the positive and suspected specimens were identified by modified acid-fast staining method and safranin-methylene blue staining method. The result showed that 13 specimens were positive by auramine-phenol staining method and confirmed by modified acid-fast staining method. 5 suspected specimens were negative as shown by the latter two methods. The best result could be obtained when auramine-phenol staining method was first used and followed by modified acid-fast staining method. This technique is simple, sensitive and reliable. It is difficult to find oocysts by safranin methylene blue staining method when the oocysts are few.

Animals↗
PubMed1989

[Scanning electron microscopic observations on adults of Angiostrongylus cantonensis].

Scanning electron microscopic observations were made on adult Angiostrongylus cantonensis, The apex of the head has a round mouth with two rows of 6 sensory papillae each around it. The papillae of the outer row are more rudimentary and inconspicuous. A pair of amphidial pores are visible on the external side of lateral papillae of the inner row. The surface of the body is covered with a circular striated cuticle and short longitudinal ridges lying between two circular cuticles. The two copulatory spicules at the posterior end of male worms are obviously different in morphology. According to their morphological characteristics, we named them "tube-like" copulatory spicule and "grooves-like" copulatory spicule. The former, when enclosed in the latter, appeared as a single one. The copulatory bursa of the males and the structures of the tail part of the female are also described.

Angiostrongylus↗
PubMed1988

Dynamic properties of membrane proteins: reversible insertion into membrane vesicles of a colicin E1 channel-forming peptide.

The binding of colicin E1 and its COOH-terminal channel-forming peptides to artificial membrane vesicles has an optimum at acidic pH values. The Mr 18,000 thermolytic peptide inserted into membrane vesicles at pH 4.0 has a limited accessibility to exogenous protease. It is converted by trypsin cleavage after Lys-381 and Lys-382 to a lower Mr 14,000 peptide. However, when the pH of a vesicle suspension to which peptide has been bound at pH 4.0 is shifted to 6.0, the accessibility to protease increased greatly. This was shown (i) by the large decrease in the amount of Mr 14,000 or Mr 18,000 peptide after the pH 4----6 shift and treatment with trypsin or Pronase, consistent with (ii) a previously observed decrease in membrane-bound radiolabeled peptide after protease treatment. (iii) When a photoactivable nitrene-generating phospholipid probe was used to label the colicin peptide inserted into the bilayer, the extent of labeling decreased by a factor of 3 when the pH was shifted from 4.0 to 6.5. (iv) Colicin peptide added to vesicles at pH 4.0 can "hop" to other vesicles if the pH and ionic strength of donor vesicles are successively increased. It is proposed that deprotonation of acidic residues in contact with the hydrophobic bilayer or the membrane surface destabilizes the inserted channel and causes it to be extruded from the membrane. The pH-dependent extrusion of the inserted colicin channel provides an example of dynamic properties of an intrinsic membrane protein.

Amino Acid Sequence↗
PubMed1985

Sympathetic ophthalmia. An immunohistochemical study of epithelioid and giant cells.

There is controversy regarding the origin of the pigment-containing epithelioid cells in the uvea of eyes with sympathetic ophthalmia. The results of the present immunocytochemical study demonstrating the presence of muramidase and S-100 protein in these cells, and the binding of peanut lectin by the pigment-containing cells support the interpretation that the pigment-containing epithelioid cells and giant cells are of monocytic (histiocytic) origin. Our study also emphasizes the diverse functional capacity of these epithelioid cells.

Epithelium↗
PubMed1984

Culture requirements of Ascaris suum larvae using a stationary multi-well system: increased survival, development and growth with cholesterol.

Ascaris suum third-stage larvae (L3) were recovered from infected rabbits and cultured in a stationary multi-well plate system. Several different culture media including Medium 199, NCTC-135, Minimum Essential Medium-Eagle, Dulbecco's Modified Eagle's Medium, RPMI 1640, McCoy's 5A and Neuman-Tytell medium were tested to determine which was best for overall larval survival, development and growth. Larvae developed from L3 to fourth-stage (L4) in all media tested, but larval survival and the yield and growth of L4 were superior in RPMI 1640. Pyruvate is an important medium component because its addition to RPMI 1640 enhanced the yield and growth of L4 while its removal from DMEM reduced larval survival and the yield and growth of L4. Cholesterol markedly enhanced larval survival and the yield and growth of L4 when added to RPMI 1640 as either a soluble supplement in Tween 80 or to a lesser degree, as a component of liposomes. The multi-well culture plate system is a convenient method for determining the effects of different media and changes in media composition on larvae in vitro.

Animals↗