Biomedical subjects

Z Pan

Publications and source records attributed to Z Pan.

At least 37 records · Page 2Linked to original sources

PubMed2001

[The 5-year death analysis in patients with nasopharyngeal carcinoma treated with radiotherapy].

OBJECTIVE: To study the main death cause of nasopharyngeal carcinoma (NPC) treated with radiotherapy for 5 years. METHOD: An analysis had been made to evaluated the 5-year death in 165 patients with NPC treated with radiotherapy. RESULT: The death correlates strongly with the clinical stage, type and radiation dose (P < 0.05). CONCLUSION: The distant metastasis and local recurrence are the main death cause of NPC.

Adolescent↗

PubMed2001

[Ultrastructure changes of the olfactory epithelium of the patients suffering from dysosmia caused by the chronic sinusitis].

OBJECTIVE: To observe the ultrastructural changes of olfactory epithelium (OE) in patients suffering from dysosmia caused by chronic sinusitis. METHODS: The specimens of olfactory epithelium were obtained from 35 patients operated for chronic sinusitis accompanied by dysosmia. According to the results of light microscope (LM) examination, the OE was divided into three groups by the types of pathological changes: normal, atrophic and respiratory epithelium metaplasia(REM). Transmission electron microscope was used to observe the ultrastructural changes of each group. RESULTS: Under the LM, the surface ultrastructure of the OE showed some abnormal changes: (1) surface microvillus of the supporting cells disappeared; (2) olfactory vesicle changed their shape due to vacuolization; (3) disappearance of canaliculus structure in the olfactory vesicle; (4) the olfactory cilia changed the shape or reduced; some of the reduced cilia underwent metaplasia. The ultrastructural changes of atrophic OE included: (1) minor and moderate atrophy: the organelles and the membrane-limited electron dense vesicles on the upper section of the supporting cells obviously decreased or disappeared, even underwent vacuolization. The basic cell degenerated; (2) serious atrophy: the turbidity of the cell structure, even double cell structure, the nuclei of the cell aggregated as the plaque and vesiculose change or karyopyknosis. As for the cytoplasm, there were the dilation of the ERs, turgidity of the mitochondrion, the disarrangement, diminution and vacuolization. Fasciculate cilia were distributed separately in the REM group. CONCLUSION: There is a positive relationship between the atrophy degree and the degree of the abnormal ultrastructural changes of the OE. The ultrastructural changes of OE in patients suffering from dysosmia caused by chronic sinusitis may provide reference for assessment of the treatment of dysosmia.

Adult↗

PubMed2001

[Biological stabilities and identification of a highly metastatic subpopulation from a human osteosarcoma cell line].

OBJECTIVE: To investigate the biological stabilities and the identification of a human highly metastatic osteosarcoma subpopulation. METHODS: Tumor pieces of the cell were inoculated into nude mice orthotopically. Lung node metastatic foci were obtained by culturing, the procedure was repeated for 3 cycles. Changes were observed in intra-tibial tumor growth, pulmonary metastatic rate in vivo, morphological characteristics, expressions of BMP, vimentin, actin, NEC and karyotype analyses of every passage in vitro. RESULTS: The intra-tibial tumor growth rates were 100%, the proliferation abilities were stable, and the pulmonary metastatic rates were higher than 80%. The expressions of BMP, vimentin, actin were positive, but the expression of NSE was negative. Its morphological characteristics the antigen-positive substances and karyotype were similar to those observed in human osteosarcoma. CONCLUSION: SOSP-M1 with very stable biological characteristics is a good model for the study of human osteosarcoma.

Animals↗

PubMed2000

Hepatocytes contribute to soluble CD14 production, and CD14 expression is differentially regulated in hepatocytes and monocytes.

CD14 presents as a glycosylphosphatidylinositol-linked membrane protein on the surface of monocytes/macrophages and as a soluble protein in the serum. Our previous studies have shown that an 80-kilobase pair (kb) genomic DNA fragment containing the human CD14 gene is sufficient to direct CD14 expression in a monocyte-specific manner in transgenic mice. In addition, we discovered that human CD14 is highly expressed in hepatocytes. Here, we report the generation of transgenic mice with either a 24- or 33-kb human CD14 genomic DNA fragment. Data from multiple transgenic lines show that neither the 24- nor the 33-kb transgenic mice express human CD14 in monocytes/macrophages. However, human CD14 is highly expressed in the liver of the 33-kb transgenic mice. These results demonstrate that human CD14 expression is regulated differently in monocytes and hepatocytes. Furthermore, we identified an upstream regulatory element beyond the 24-kb region, but within the 33-kb region of the human CD14 gene, which is critical for CD14 expression in hepatocytes, but not in monocytes/macrophages. Most importantly, the data demonstrate that the liver is one of the major organs for the production of soluble CD14. These transgenic mice provide an excellent system to further explore the functions of soluble CD14.

Animals↗

PubMed2000

Scale-up study on suspension cultures of Taxus chinensis cells for production of taxane diterpene.

Suspension cells of Taxus chinensis were cultivated in both shake flasks and bioreactors. The production of taxuyunnanine C (TC) was greatly reduced when the cell cultures were transferred from shake flasks to bioreactors. Oxygen supply, shear stress and stripping-off of gaseous metabolites were considered as potential factors affecting the taxane accumulation in bioreactors. The effects of oxygen supply on the cell growth and metabolism were investigated in a stirred tank bioreactor by altering its oxygen transfer rate (OTR). It was found that both the pattern and amount of TC accumulation were not much changed within the range of OTR as investigated. Comparative studies on the cell cultivation in low shear and high shear generating bioreactors suggest that the decrease of TC formation in bioreactors was not due to the different shear environments in different cultivation vessels. An incorporation of 2% CO(2) in the inlet air was beneficial for the cell growth, but did not improve the TC production in bioreactors. Furthermore, the effects of different levels of ethylene addition into the inlet air on the cell growth and TC production were investigated in a bubble column reactor. The average cell growth rate increased from 0.146 to 0.204 d(-1) as the ethylene concentration was raised from 0 to 50 ppm, and both the content and production of TC were also greatly improved by ethylene addition. At an ethylene concentration of 18 ppm, the highest TC content and volumetric production in the reactor reached 13.28 mg/(g DW) and 163.7 mg/L, respectively, which were almost the same as those in shake flasks. Compared with the control reactor (bubble column without ethylene supplementation), the maximum TC content was increased by 82% and the total production of TC was doubled. The results indicate that ethylene is a key factor in scaling up the process of the suspension cultures of T. chinensis from a shake flask to a bioreactor.

Journal Article↗

PubMed2000

Depletion of intracellular Ca2+ by caffeine and ryanodine induces apoptosis of chinese hamster ovary cells transfected with ryanodine receptor.

Recent studies have suggested a central role for Ca(2+) in the signaling pathway of apoptosis and certain anti-apoptotic effects of Bcl-2 family of proteins have been attributed to changes in intracellular Ca(2+) homeostasis. Here we report that depletion of Ca(2+) from endoplasmic reticulum (ER) leads to apoptosis in Chinese hamster ovary cells. Stable expression of ryanodine receptor (RyR) in these cells enables rapid and reversible changes of both cytosolic Ca(2+) and ER Ca(2+) content via activation of the RyR/Ca(2+) release channel by caffeine and ryanodine. Sustained depletion of the ER Ca(2+) store leads to apoptosis in Chinese hamster ovary cells, whereas co-expression of Bcl-xL and RyR in these cells prevents apoptotic cell death but not necrotic cell death. The anti-apoptotic effect of Bcl-xL does not correlate with changes in either the Ca(2+) release process from the ER or the capacitative Ca(2+) entry through the plasma membrane. The data suggest that Bcl-xL likely prevents apoptosis of cells at a stage downstream of ER Ca(2+) release and capacitative Ca(2+) entry.

Animals↗

PubMed2000

GFP-centrin as a marker for centriole dynamics in living cells.

A long-standing puzzle in cell biology is the question of how cells generate one and only one new centrosome in each cell cycle and what is the role of the centriole pair in this process. In this study, the introduction of GFP-centrin into cultured cells allows direct visualization of centriole behavior in living cells and in real time. Using this method, centriole dynamics can be observed throughout the cell cycle and following a variety of experimental treatments. Our studies demonstrate that the biogenesis of new centrioles from individual members of a preexisting centriole pair is asynchronous: the older centriole initiates assembly of a new daughter centriole before the younger centriole initiates assembly of its daughter.

Calcium-Binding Proteins↗

PubMed2000

Radiographic evaluation of surgical clips is better than ultrasound for defining the lumpectomy cavity in breast boost treatment planning: a prospective clinical study.

PURPOSE: Breast radiotherapy (BrRT) often includes a "boost" to the lumpectomy bed. Selection of an appropriate electron energy and field size is based upon the dimensions and location of the surgical cavity. This study was performed to confirm our impression that ultrasound (US) inadequately defines the volume at risk compared to radiographic evaluation of surgical clips placed within the operative bed at the time of lumpectomy. METHODS AND MATERIALS Twenty-nine women treated with BrRT at our institution between 1996-1998 were prospectively identified as having surgical clips within the lumpectomy cavity. These patients underwent both US evaluation and radiographic evaluation of the clips to independently define two sets of transverse (T), longitudinal (L), and depth (D) measurements for each cavity. Volumes (V) were calculated for each method, assuming the cavity to be a box (V = T x L x D). Twenty-one women began BrRT following a median postoperative interval of 6 weeks (Group A), and 8 after 24 weeks (Group B) due to delivery of systemic therapy. RESULTS: Dimensions derived by US were smaller than the clip method in 22/29 of T, 25/29 of L, and 23/29 of D, or 80% of all linear measurements. A paired t-test demonstrated the difference between the methods to be statistically significant: T: p = 0.0004; L: p = 0.0001; D: p = 0.0004; and V: p = 0.0001. This underestimation by US did not fit any predictable pattern. Although the mean difference between methods (clips - US) was only 1.3, 1.9, and 1.1 cm for T, L, and D, respectively, differences ranged up to 5. 7, 9.2, and 5.5 cm for T, L, and D. The bias toward underestimation of V by US was significantly greater for Group B than Group A (p = 0. 03). CONCLUSIONS: US significantly underestimates all three dimensions of the lumpectomy cavity and hence the volume at risk compared to radiographic evaluation of surgical clips. Breast-conserving surgery should include placement of clips at the margins of the lumpectomy cavity (superior, inferior, medial, lateral, and posterior) to aid in radiotherapy treatment planning. US should not be utilized to guide the design of the boost field as it will result in inappropriate selection of lower electron energies and smaller field sizes (geographical miss), particularly among patients who receive chemotherapy prior to breast radiotherapy.

Breast Neoplasms↗

PubMed2000

Urokinase plasminogen activator/urokinase-specific surface receptor expression and matrix invasion by breast cancer cells requires constitutive p38alpha mitogen-activated protein kinase activity.

Overexpression of urokinase plasminogen activator (uPA) and its receptor (uPAR) has been well documented in a wide variety of tumor cells. In breast cancer, expression of uPA/uPAR is essential for tumor cell invasion and metastasis. However, the mechanism responsible for uPA/uPAR expression in cancer cells remains unclear. In the studies reported here, we show that endogenous p38 MAPK activity correlates well with breast carcinoma cell invasiveness. Treatment of highly invasive BT549 cells with a specific p38 MAPK inhibitor SB203580 diminished both uPA/uPAR mRNA and protein expression and abrogated the ability of these cells to invade matrigel, suggesting that p38 MAPK signaling pathway is involved in the regulation of uPA/uPAR expression and breast cancer cell invasion. We also demonstrated that SB203580-induced reduction in uPA/uPAR mRNA expression resulted from the de- stabilization of uPA and uPAR mRNA. Finally, by selectively inhibiting p38alpha or p38beta MAPK isoforms, we demonstrate that p38alpha, rather than p38beta, MAPK activity is essential for uPA/uPAR expression. These studies suggest that p38alpha MAPK signaling pathway is important for the maintenance of breast cancer invasive phenotype by promoting the stabilities of uPA and uPAR mRNA.

Breast Neoplasms↗

PubMed2000

Cloning and characterization of a novel human ubiquitin-specific protease, a homologue of murine UBP43 (Usp18).

The ubiquitin-specific proteases (UBP) are a family of enzymes that cleave ubiquitin from ubiquitinated protein substrates. We have recently cloned UBP43, a novel member of this family from AML1-ETO knock-in mice. To analyze the role of UBP43 in hematopoiesis and leukemogenesis, we have cloned a full-length human UBP43 cDNA by screening a human monocytic cDNA library as well as by 5'- and 3'-rapid amplification of cDNA ends analyses. This cDNA encodes a polypeptide of 372 amino acids with all of the structural motifs of a deubiquitinating enzyme. The human UBP43 mRNA is strongly expressed in human liver and thymus. Transfection analysis has demonstrated that UBP43 is a nuclear protein. Interestingly, the gene encoding human UBP43 maps to chromosome 22q11.2. This region, known as DiGeorge syndrome critical region, contains a minimal area of 2 Mb and is consistently deleted in DiGeorge syndrome and related disorders. The syndrome is marked by thymic aplasia or hypoplasia, parathyroid hypoplasia, or congenital cardiac abnormalities. Taken together, our results broaden the understanding of a new human ubiquitin-specific protease, UBP43, and suggest that this gene may also be related to DiGeorge syndrome.

Amino Acid Sequence↗

PubMed2000

Targeted disruption of the galectin-3 gene results in attenuated peritoneal inflammatory responses.

Galectin-3 is a member of a growing family of beta-galactoside-binding animal lectins. Previous studies have demonstrated a variety of biological activities for this protein in vitro, including activation of cells, modulation of cell adhesion, induction of pre-mRNA splicing, and regulation of apoptosis. To assist in fully elucidating the physiological and pathological functions of this protein, we have generated galectin-3-deficient (gal3(-/-)) mice by targeted interruption of the galectin-3 gene. Gal3(-/-) mice consistently developed fewer inflammatory cell infiltrations in the peritoneal cavities than the wild-type (gal3(+/+)) mice in response to thioglycollate broth treatment, mainly due to lower numbers of macrophages. Also, when compared to cells from gal3(+/+) mice, thioglycollate-elicited inflammatory cells from gal3(-/-) mice exhibited significantly lower levels of NF-kappaB response. In addition, dramatically different cell-spreading phenotypes were observed in cultured macrophages from the two genotypes. Whereas macrophages from gal3(+/+) mice exhibited well spread out morphology, those from gal3(-/-) mice were often spindle-shaped. Finally, we found that peritoneal macrophages from gal3(-/-) mice were more prone to undergo apoptosis than those from gal3(+/+) mice when treated with apoptotic stimuli, suggesting that expression of galectin-3 in inflammatory cells may lead to longer cell survival, thus prolonging inflammation. These results strongly support galectin-3 as a positive regulator of inflammatory responses in the peritoneal cavity.

Animals↗

PubMed2000

A cellular mechanism for the bidirectional pain-modulating actions of orphanin FQ/nociceptin.

Orphanin FQ/nociceptin (OFQ/N) and its receptor share substantial structural features and cellular actions with classic opioid peptides and receptors, but have distinct pharmacological profiles and behavioral effects. Currently there is an active debate about whether OFQ/N produces hyperalgesia or analgesia. Using a well-defined brainstem pain-modulating circuit, we show that OFQ/N can cause either an apparent hyperalgesia by antagonizing mu opioid-induced analgesia or a net analgesic effect by reducing the hyperalgesia during opioid abstinence. It presumably produces these two opposite actions by inhibiting two distinct groups of neurons whose activation mediates the two effects of opioid administration. OFQ/N antagonism of the hyperalgesia may have significance for the treatment of opioid withdrawal and sensitized pain.

Analgesia↗

PubMed2000

Effects on eyes and nose in humans after experimental exposure to airborne office dust.

To test sensory irritation symptoms and physiological effects on humans caused by airborne office dust, ten subjects were exposed to both clean air and airborne non-industrial office dust for 3 h in a climate chamber. The average dust concentration in exposure sessions was 394 micrograms/m3 total suspended dust (TSD). Tear film break-up time, foam formation in the eye canthus, conjunctival epithelial damage, nasal volume, and nasal minimal cross-sectional area were assessed. Tear film break-up time decreased significantly after dust exposure and nasal volume showed a tendency to decrease. In a questionnaire investigation, significant effects were found from the questions: "facial skin humidity", "throat irritation", "feeling needs of coughing", "dry nose", "concentration difficulty", and "headache". Additionally, the intensity of the questions "facial skin humidity", "dry nose", "body skin temperature", "sluggishness", and "sleepiness" worsened over time. A correlation analysis showed that perceived "air quality" was significantly correlated with "dry eyes", "eye irritation", "facial skin irritation", "nose irritation", and "feeling stressed by chamber occupancy" for subacute responses, and with "odor intensity" for acute responses. This supports that the perceived air quality may be a function of odor and irritation symptoms. A number of localized symptoms of irritation (e.g. dry nose, throat irritation, coughing) and of general symptoms (e.g. sluggishness, sleepiness, headache, ability to concentration) were mutually correlated acutely and subacutely. These results indicate that non-industrial office dust may cause physiological changes and sensory symptoms in eyes and nose and that these effects have different time courses.

Adult↗

PubMed2000

Expression of histo-blood group antigens by lipopolysaccharides of Helicobacter pylori strains from asian hosts: the propensity to express type 1 blood-group antigens.

Past studies have shown that the cell surface lipopolysaccharides (LPSs) of the ubiquitous human gastric pathogen Helicobacter pylori (a type 1 carcinogen) isolated from people residing in Europe and North America express predominantly type 2 Lewis x (Le(x)) and Le(y) epitopes and, infrequently, type 1 Le(a), Le(b), and Le(d) antigens. This production of Lewis blood-group structures by H. pylori LPSs, similar to those found in the surfaces of human gastric cells, allows the bacterium to mimic its human niche. In this study, LPSs of H.pylori strains extracted from patients living in China, Japan, and Singapore were chemically and serologically analyzed. When compared with Western H.pylori LPSs, these Asian strains showed a stronger tendency to produce type 1 blood groups. Of particular interest, and novel observations in H.pylori, the O-chain regions of strains F-58C and R-58A carried type 1 Le(a) without the presence of type 2 Le(x), strains R-7A and H607 were shown to have the capability of producing the type 1 blood group A antigen, and strains CA2, H507, and H428 expressed simultaneously the difucosyl isomeric antigens, type 1 Le(b) and type 2 Le(y). The apparent proclivity for the production of type 1 histo-blood group antigens in Asian H.pylori LPSs, as compared with Western strains, may be an adaptive evolutionary effect in that differences in the gastric cell surfaces of the respective hosts might be significantly dissimilar to select for the formation of different LPS structures on the resident H.pylori strain.

ABO Blood-Group System↗

PubMed2000

Differences in genotypes of Helicobacter pylori from different human populations.

DNA motifs at several informative loci in more than 500 strains of Helicobacter pylori from five continents were studied by PCR and sequencing to gain insights into the evolution of this gastric pathogen. Five types of deletion, insertion, and substitution motifs were found at the right end of the H. pylori cag pathogenicity island. Of the three most common motifs, type I predominated in Spaniards, native Peruvians, and Guatemalan Ladinos (mixed Amerindian-European ancestry) and also in native Africans and U.S. residents; type II predominated among Japanese and Chinese; and type III predominated in Indians from Calcutta. Sequences in the cagA gene and in vacAm1 type alleles of the vacuolating cytotoxin gene (vacA) of strains from native Peruvians were also more like those from Spaniards than those from Asians. These indications of relatedness of Latin American and Spanish strains, despite the closer genetic relatedness of Amerindian and Asian people themselves, lead us to suggest that H. pylori may have been brought to the New World by European conquerors and colonists about 500 years ago. This thinking, in turn, suggests that H. pylori infection might have become widespread in people quite recently in human evolution.

Amino Acid Isomerases↗

PubMed2000

Evaluation of a sexuality education program for young adolescents in Jamaica.

Despite their increasing numbers, few of the sexuality education and pregnancy prevention programs in developing countries have been evaluated. This study, conducted in 1995-1997, assesses the impact of a school-based sexuality education program, the Grade 7 Project, on 945 Jamaican seventh graders (aged 11-14) and their initiation of sexual activity and use of contraception at first intercourse, as well as the knowledge and attitudes that influence their behaviors. Using a quasi-experimental design, the study measured the effects of the Grade 7 Project when the nine-month intervention was completed (short term) and one year after that (long term). Multivariate logistic regression analysis indicated that the project had no effect on initiation of sexual activity, but it had a positive short-term impact on use of contraception at first intercourse (P = .08); adolescents in the intervention group were more than twice as likely to use contraception. The project also had a positive short-term influence on several aspects of the adolescents' knowledge of and attitudes about sexuality and pregnancy. The modest impact of the Grade 7 Project is encouraging, as school-based sexuality education programs of limited duration rarely have a long-term impact. Moreover, competing socioeconomic and cultural forces in Jamaica encourage early sexuality and parenthood among adolescents. The use of more participatory teaching methods and smaller class sizes might strengthen the Grade 7 Project and enhance its impact.

Adolescent↗

PubMed2000

Thrombin causes pseudopod detachment via a pathway involving cytosolic phospholipase A2 and 12/15-lipoxygenase products.

Thrombin causes rapid pseudopod detachment and shortening in Dunning rat prostatic carcinoma (MAT-Lu) cells. As seen by interference reflection microscopy and by immunofluorescence analysis with antibodies to paxillin and talin, the primary event is disassembly of adhesion sites. Biochemically, thrombin is a potent activator of cytosolic phospholipase A2 and increases eicosanoid production in these cells. The pseudopod effects are blocked by lipoxygenase (but not cyclooxygenase) inhibitors. Arachidonic acid and 12(S)-hydroxyeicosatetraenoic acid or 15(S)-hydroxyeicosatetraenoic acid mimic the thrombin effect. We conclude that in certain cancer cells, thrombin is a pseudopod repellent that exerts its effect via a cascade involving cytosolic phospholipase A2, 12/15-lipoxygenase, and 12(S)- and/or 15(S)-hydroxyeicosatetraenoic acid.

Animals↗

PubMed2000

A phase I/II trial of paclitaxel, carboplatin, and gemcitabine in untreated patients with advanced non-small cell lung cancer.

Paclitaxel and carboplatin is widely used in the treatment of patients with advanced non-small cell lung cancer (NSCLC); however, median survival remains < 1 year. One strategy to improve survival is to add a third active drug with a differing mechanism of action. Gemcitabine is a novel antimetabolite with considerable activity in NSCLC. The primary objective of this Phase I/II study was to determine the maximally tolerated dose of gemcitabine administered with fixed doses of paclitaxel and carboplatin in untreated patients with advanced NSCLC.

Adenocarcinoma↗