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Biomedical subjects

X Lin

Publications and source records attributed to X Lin.

At least 271 records · Page 15Linked to original sources
PubMed1998

[A modified laryngectomy combined with radical neck dissection for late-staged supraglottic carcinoma].

8 cases of supraglottic or transglottic carcinoma with neck lymphatic metastasis received a modified laryngectomy or subtotal laryngectomy combined with radical neck dissection. Laryngeal function was reconstructed in 3 of them. No postoperative complication occurred. All cases survived uneventfully through a five-year following up, except one who died of neck lymphatic and lung metastasis. The indication, procedure and advantage of this operation are discussed in this article.

Aged↗
PubMed1998

[A clinical study of six cases of Pneumocystis carinii pneumonia].

OBJECTIVE: To heighten the awareness of pneumocystis carinii pneumonia. METHOD: Six cases of pneumocystis carinii pneumonia were retrospectively analyzed. RESULT: The underlying diseases were leukemia, lymphoma, renal transplantation and autoimmune hemolytic anemia. The clinical features were dyspnea, cough and fever. X rays typically showed a bilateral diffuse or patchy interstitial infiltrate. Three cases complicated with acute respiratory failure showed hypoxemia, intrapulmonary shunt and reduced compliance resembling ARDS. CPAP/PEEP was required. High-level PEEP (> 1.47 kPa) can be applied to the refractory hypoxemia. SMZco and dapsone were the initial choice of treatment. CONCLUSION: The prognosis of pneumocystis carinii pneumonia with acute respiratory failure was poor. Aggressive early diagnosis and treatment were critical to improve survival.

Acute Disease↗
PubMed1998

[Math-model of efficient cultivation of Angelica sinensis].

Using two-time general rotation-constitution design, the math-mdele has been founded about Angelica sinensis prodution efficiency and quantity of nitrogen, phosphorus and potassium to use by doing experiments in many different spots and production demonstration for testing and verifying. Accordin to the modle, computer is used to simulate the better, through which people can get fresh Chinese angelica over 500 Kg per mu and also net income over 500 yuan per mu. It shows that this is the best combination. 95% density riliability for this plan is 6860-7600 plants, pure nitrogen 18.75-22.2 Kg, P2O5 9.1-11.1 Kg and K2O 4.46-5.37 Kg One mu. Proportion for nitrogen, phosphorus, potassium is 1:0.49:0.24.

Angelica↗
PubMed1998

[Study on the supercritical-CO2 fluid extraction of Prunus mandshurica oils].

The paper reported technological study on extracting Prunus mandshurica oils by supercritical-CO2 fluid, mainly researched the influence of pressure, temperature, time and flow rate of CO2 on the oil yield, determined optimum technology of extracting the oils, compared the oils from SFE-CO2 and traditional technology.

Carbon Dioxide↗
PubMed1998

[The application of retinotomy and retinectomy for complicated retinal detachment].

OBJECTIVE: To investigate the techniques, therapeutic effects, indications, complications and control of retinotomy and retinectomy for complicated retinal detachment. METHODS: Based on the preliminary report of retinotomy and retinectomy, 36 eyes of 36 patients of complicated retinal detachment were operated on and followed-up for 3-12 months. The operative technique included buckling, vitrectomy, peeling, retinotomy and retinectomy, intraocular tamponade and laser treatment. RESULTS: Retina was reattached in 32 eyes in operation. Retinal detachment was recurrent in 8 eyes in followed-up in which retina was reattached again in 3 eyes by second operation. The last successful rate was 75% (in 27 eyes). The visual acuity was worse than funger conter in 33 eyes and worse than 0.05 in 3 eyes before operation. The visual acuity was better than 0.05 in 20 eyes (55.5%) after operation. The complications included bleeding, retinotomy expanding, complicated cataract, hypotony and so on. CONCLUSION: Retinotomy and retinectomy can improve the curative effect of complicated retinal detachment. But the complications of these operation were severe. The indications should be well controlled.

Follow-Up Studies↗
PubMed1998

[Characterization of spontaneous transplant tolerance exemplified by orthotopic liver transplantation: significance of Fas ligand induced programmed cell death].

For the first time, this study provides strong evidence that hepatocytes express functional Fas-ligand protein after orthotopic liver transplantation in specific allogeneic strain combinations. Fas-L expression correlates with intra-graft elimination of alloreactive T cells and subsequent tolerance induction. Thus, detection of Fas-L offers the possibility to be used as a marker protein for tolerized liver transplants.

Animals↗
PubMed1998

[Anisotropic absorption spectra in YAlO3: (Nd3+ and Lu3+) single crystal].

Absorption spectra of YAlO3: (Nd3+, Lu3+) single crystals for the three crystallographic axes were investigated at room temperature. The absorption band intensities distinctly revealed the anisotropy of YAlO3: (Nd3+, Lu3+). The Judd-Ofelt theory was modified and applied to the treatment of the anisotropic absorption spectra. The absorption cross sections and the electric dipole oscillator strengths of various bands were calculated for three crystallographic axes of YAlO3: (Nd3+, Lu3+) crystals. Three sets of phenomenological parameters omegat(alpha) were determined. The validity of the modified Judd-Ofelt approach is discussed in detail. Moreover, we explained the anisotropy of the optical absorption of YAlO3: (Nd3+, Lu3+).

English Abstract↗
PubMed1998

CG island methylation changes near the GSTP1 gene in prostatic intraepithelial neoplasia.

Prostate intraepithelial neoplasia (PIN) is a purported prostate cancer precursor lesion and a candidate biomarker for efficacy assessment in prostate cancer chemoprevention trials. Loss of expression of the pi-class glutathione S-transferase enzyme GSTP1, which is associated with the hypermethylation of deoxycytidine residues in the 5'-regulatory CG island region of the GSTP1 gene, is a near-universal finding in human prostate cancer. GSTP1 expression was assessed by immunohistochemistry in 60 high-grade PIN samples adjacent to and distant from prostate adenocarcinoma. Whereas abundant enzyme polypeptide expression was evident in all normal prostatic tissues, all samples of high-grade PIN and adenocarcinoma were completely devoid of GSTP1. DNA from 10 high-grade PIN lesions was analyzed for GSTP1 CG island methylation changes using a PCR technique targeting a polymorphic (ATAAA)n repeat sequence in the promoter region of the GSTP1 gene. Somatic GSTP1 CG island methylation changes were detected in DNA from 7 of the 10 PIN lesions. Allele discrimination was possible for 5 of the 10 DNA samples: 2 of the 5 samples exhibited DNA methylation changes at both alleles; whereas 3 samples displayed no DNA methylation changes at either allele. GSTP1 CG island methylation changes were present in each of the five homozygous samples. Hypermethylation of the 5'-regulatory region of the GSTP1 gene may serve as an important molecular genetic biomarker for both prostate cancer and PIN. The finding of frequent GSTP1 methylation changes in PIN and prostate cancer supports a role for PIN lesions as a prostate cancer precursor and may provide insight to the molecular pathogenesis of prostate cancer.

Adenocarcinoma↗
PubMed1998

Hyperbaric oxygen as a signal transducer: upregulation of platelet derived growth factor-beta receptor in the presence of HBO2 and PDGF.

The purpose of this study was to test the hypothesis that hyperbaric oxygen (HBO2) may function by modifying the signal transduction pathway of growth factors or their receptors, or both. Studies were conducted with platelet derived growth factor (PDGF) and HBO2 using an established rabbit ear wound model. PDGF, a dimeric compound composed of A chain and B chain components, is found as PDGF-A, AB, and BB. It exerts its effects on cells by binding to one of two membrane-bound receptors, the alpha receptor or the beta receptor. Acutely ischemic wounds in rabbit ears were treated with saline or PDGF-BB and then animals were treated with hyperbaric air or oxygen at 2 atm abs (202.6 kPa). Hyperbaric air was without significant effect compared with control rabbits who breathed air at ambient pressure. Combined treatment with HBO2 plus PDGF-BB was synergistic in upregulating mRNA for PDGF-beta receptor. No treatments, whether alone or in combination, altered mRNA levels for PDGF-alpha receptor or for PGDF-A.

Animals↗
PubMed1997

A Study on the Chemical Heterogeneity of Active Surface of Solid Catalysts

A method that can be used to characterize the chemical heterogeneity of active surface of solid catalyst is given. The chemical adsorption behavior of three adsorbates on Ni-W/F-Al2O3-SiO2 catalyst and supported Ni catalyst has been investigated. On the basis of fractal geometry, the roughness fractal dimension (Dr) and the chemisorption fractal dimension (Dc) of two kinds of catalyst are estimated. We use the difference between Dc and Dr to characterize the chemical heterogeneity of active sites on the catalytic surface. As a result, the chemical heterogeneity of the acid sites of Ni-W/F-Al2O3-SiO2 catalyst is very great. As for supported Ni catalyst, the chemical heterogeneity of active sites decreased when impregnating operation times in preparation of the catalyst increased. After impregnated four times, the chemical heterogeneity of its active surface of supported Ni catalyst is eliminated. Copyright 1997 Academic Press. Copyright 1997Academic Press

Journal Article↗
PubMed1997

Alteration of glycosylation renders HIV sensitive to inactivation by normal human serum.

Retroviruses from various mammalian species, excluding humans, are effectively inactivated in normal human serum (NHS). Recent studies have shown that NHS inactivation of retroviruses occurs through natural Ab recognition of a terminal glycosidic moiety on the viral envelope that is acquired during replication in the host cell. This carbohydrate structure (the alpha-galactosyl epitope) is expressed on the cells of most mammals, with the exception of humans and other Old World primates. In this study, NHS sensitivity of HIV was assessed following viral propagation in human cells that were manipulated to express the alpha-galactosyl epitope. HUT-78 cells were transduced with an exogenous alpha1-3-galactosyl transferase gene, which codes for the terminal glycosyl transferase responsible for generation of the alpha-galactosyl epitope. The transduced HUT-78 cells expressed high levels of the alpha-galactosyl epitope on their membrane surface, rendering them sensitive to killing in NHS. Similarly, HIV passaged through these cells acquired the alpha-galactosyl epitope in association with the envelope glycoprotein gp120 and was also effectively inactivated in NHS. Viral inactivation was abolished by the addition of a synthetic disaccharide that contains the alpha-galactosyl epitope, indicating that virolysis is mediated by anti-alpha-galactosyl natural Ab. These results demonstrate that, like other retroviruses bearing the alpha-galactosyl epitope, HIV modified to express this epitope is inactivated in NHS. Furthermore, these data suggest that expression of the alpha-galactosyl epitope on the surface of viruses may have implications in the interspecies transmission of such viruses to humans.

Animals↗
PubMed1997

Kinetic properties of saquinavir-resistant mutants of human immunodeficiency virus type 1 protease and their implications in drug resistance in vivo.

In order to study the basis of resistance of human immunodeficiency virus, type 1 (HIV-1), to HIV-1 protease inhibitor saquinavir, the catalytic and inhibition properties of the wild-type HIV-1 protease and three saquinavir resistant mutants, G48V, L90M, and G48V/L90M, were compared. The kinetic parameter kcat/Km was determined for these proteases using eight peptide substrates whose sequences were derived from the natural processing site sequences of HIV-1. The kcat/Km values were determined using conventional steady-state kinetics as well as initial velocities of mixed substrate cleavages under the condition where the substrate concentrations [S]o << Km. The independently determined kcat and Km values for some of the substrates confirmed the accuracy of the mixed-substrate method and also permitted the calculation in all cases of true rather than relative kcat/Km values. The Ki values were also determined. Using a previously described kinetic model [Tang, J., & Hartsuck, J. A. (1995) FEBS Lett. 367, 112-116], the relative processing activities of HIV-1 protease variants were estimated in the saquinavir concentration range of 0-10(-7) M. Although the protease activity of G48V, L90M, and G48V/L90M are only about 10, 7, and 3% of that of the wild-type HIV-1 protease in the absence of inhibitor, the resistance tendencies of the three mutants are clearly manifest by relatively less activity loss as inhibitor concentration becomes higher. Also, the ratios of the activities of the four protease species at certain saquinavir concentrations appear to correlate with the population ratios of the four protease species at different time points of clinical trials. This correlation suggests that the population ratio of the protease species is driven by in vivo saquinavir concentration, which appears to be in the range 10(-10)-10(-9) M during the clinical trials.

Dose-Response Relationship, Drug↗
PubMed1997

Ethnic differences in the length of the menstrual cycle during the postmenarcheal period.

In 1989, 125 African-American and 123 European-American girls aged 12-14 years were enrolled in a 2-year study in which they maintained a menstrual calendar, recording the date and amount of menstrual bleeding. Weight, exercise, and stress during the previous week were recorded at the start of each menstrual cycle. Although only minor ethnic differences were observed in expected cycle length (29.3 vs. 28.8 days for European-American and African-American girls, respectively), more prominent differences were observed in the between-subjects standard deviation of cycle length (2.9 vs. 2.2 days, respectively) and in the odds of having a cycle longer than 45 days (odds ratio=1.86, 95% confidence interval 1.17-2.97) for European-American compared with African-American girls. Low weight for height and high levels of exercise increased the probability of having a cycle longer than 45 days and decreased expected cycle length of 13- to 45-day cycles. Additional investigation of potential ethnic differences in menstrual cycle characteristics is warranted.

Adolescent↗
PubMed1997

The 90-kDa ribosomal S6 kinase (pp90rsk) phosphorylates the N-terminal regulatory domain of IkappaBalpha and stimulates its degradation in vitro.

Nuclear factor kappaB (NF-kappaB) is a eukaryotic member of the Rel family of transcription factors whose biological activity is post-translationally regulated by its assembly with various ankyrin-rich cytoplasmic inhibitors, including IkappaBalpha. Expression of NF-kappaB in the nucleus occurs after signal-induced phosphorylation, ubiquitination, and proteasome-mediated degradation of IkappaBalpha. The induced proteolysis of IkappaBalpha unmasks the nuclear localization signal within NF-kappaB, allowing its rapid migration into the nucleus, where it activates the transcription of many target genes. At present, the identity of the IkappaBalpha kinase(s) that triggers the first step in IkappaBalpha degradation remains unknown. We have investigated the potential function of the 90-kDa ribosomal S6 kinase, or pp90(rsk), as a signal-inducible IkappaBalpha kinase. pp90(rsk) lies downstream of mitogen-activated protein (MAP) kinase in the well characterized Ras-Raf-MEK-MAP kinase pathway that is induced by various growth factors and phorbol ester. We now show that pp90(rsk), but not pp70(S6K) or MAP kinase, phosphorylates the regulatory N terminus of IkappaBalpha principally on serine 32 and triggers effective IkappaBalpha degradation in vitro. When co-expressed in vivo in COS cells, IkappaBalpha and pp90(rsk) readily assemble into a complex that is immunoprecipitated with antibodies specific for either partner. While phorbol 12-myristate 13-acetate produced rapid activation of pp90(rsk), in vivo, other potent NF-kappaB inducers, including tumor necrosis factor alpha and the Tax transactivator of human T-cell lymphotrophic virus, type I, failed to activate pp90(rsk). These data suggest that more than a single IkappaBalpha kinase exists within the cell and that these IkappaBalpha kinases are differentially activated by different NF-kappaB inducers.

Animals↗
PubMed1997

Reexpression of the major protein kinase C substrate, SSeCKS, suppresses v-src-induced morphological transformation and tumorigenesis.

SSeCKS (pronounced essex) encodes a major protein kinase C substrate, the expression of which is down-regulated in src- and ras-transformed rodent fibroblasts but not in raf-transformed rodent fibroblasts (X. Lin et al., Mol. Cell. Biol., 15: 2754-2762, 1995). Using a panel of ras-transformed or revertant Rat-6 cells that exhibit selective parameters of transformation, we show that down-regulation of SSeCKS correlates with anchorage-independent growth. Cotransfection of NIH3T3 fibroblasts with an SSeCKS expression plasmid decreased 6-30-fold the ability of a v-src expressor plasmid to induce colonies in soft agar. To differentiate between possible tumor suppressive or growth-inhibitory effects of SSeCKS, we developed conditionally transformed cell lines (expressing ts72v-src) with tetracycline-regulated SSeCKS expression. SSeCKS suppressed the ability of v-src to induce increased cellular refractility, focus formation, soft agar colony formation, in vitro invasiveness in Matrigel, and growth in low serum (0.5%) but did not inhibit cell proliferation in high serum (10%) at the permissive (35 degrees C) temperature for src kinase activity. However, at the nonpermissive (39.5 degrees C) temperature, SSeCKS induced growth arrest. SSeCKS expression did not affect: (a) the protein level, in vivo or in vitro kinase activity of ts72src; (b) the activity of jun NH2-terminal kinase; and (c) the level of mitogen-activated protein kinase (extracellular signal-regulated kinase 2) protein. However, extracellular signal-regulated kinase 2 activity was induced 5-10-fold by SSeCKS in the presence of active src. SSeCKS reversed the ability of v-src to decrease the formation of vinculin-associated adhesion plaques, actin-based stress fibers, and filopodia structures. These data suggest a tumor suppressive role for SSeCKS via the control of cytoskeletal architecture and cell signaling.

3T3 Cells↗
PubMed1997

Dose- and time-dependent relations between infective Anopheles inoculation and outcomes of Plasmodium falciparum parasitemia among children in western Kenya.

Blood-stage level Plasmodium falciparum infection (parasitemia density) is generally elevated prior to, or at the time of, clinical presentation of severe pediatric malaria episodes. Intensity of exposure to infective Anopheles mosquito bites is a suspected determinant of higher density parasitemia. Analyses of entomologic and parasitologic data collected in 1986-1987 were conducted to investigate whether the dose of infective bites predicted the incidence or degree of P. falciparum parasitemia in Kenyan children < 6 years old. At 21 consecutive 30-day intervals, a new cohort (n approximately 50 each) was enrolled, cured of malaria parasites, and monitored over 84 days for recurrent parasitemia. Outcomes included time to parasitemia, time to parasitemia > or = 5,000/microliter, and parasitemia density. Ecologic and individual-level analyses were conducted. The mean infective bite exposure experienced by each cohort was significantly associated with the incidence of parasitemia (age-adjusted r2 = 0.38, p = 0.022) and more strongly associated with the incidence of parasitemia > or = 5,000/microliter (age-adjusted r2 = 0.72, p < 0.001). The infective bite dose, analyzed as a time-dependent covariate, was associated with a 2.8 times higher rate of parasitemia > or = 5,000/microliter among children exposed to > or = 1 infective bite per day as compared with the referent (rate ratio (RR) = 2.82, 95% confidence interval (CI) 2.24-3.56). Cumulative infective bite exposure, exposure duration, and age were significant predictors of recurrent parasitemia density in multiple linear regression analyses. The results support the contention that reductions in P. falciparum transmission intensity, in the absence of complete elimination, will reduce higher level parasitemia among African children.

Animals↗
PubMed1997

Insulin-like growth factor I (IGF-I) is a critical trophic factor for developing cerebellar granule cells.

In this study we showed that insulin-like growth factor I (IGF-I) directly increased cell survival in pure cerebellar granule cell cultures established from postnatal day 7 (P7) mice. The maximal survival-promoting effect could be obtained at low IGF-I concentrations (3-5 ng/ml). Withdrawal of IGF-I from differentiated granule neurons resulted in neuronal death which suggests that IGF-I has a survival-promoting effect on differentiated granule neurons. Furthermore, the survival-promoting effect of IGF-I was not attenuated by the addition of K252a, a selective blocker of Trk signaling, indicating that the survival-promoting effect of IGF-I did not require or was not mediated by endogenously produced neurotrophins, such as BDNF and NT3. Further experiments also suggest that IGF-I stimulates proliferation of granule cell precursors and allows terminal granule neuron differentiation to occur, as indicated by the expression of terminal differentiation markers MEF2A and GABA(A) alpha6. Thus, IGF-I could potentially function as both a mitogen and a trophic factor for developing granule cells. This dual action of IGF-I may be important in regulating granule neuron number.

Animals↗