Biomedical subjects

Z Pan

Publications and source records attributed to Z Pan.

At least 55 records · Page 3Linked to original sources

PubMed2000

[An experimental study on treatment of limbal alkali burn by allograft transplantation with cultured stem cells on amniotic membrane].

OBJECTIVE: To study the treatment of rabbit limbal alkali burn by cultured limbal stem cells growing on amniotic membrane for allograft transplantation. METHODS: After the primary culture of the rabbit corneal stem cells, they were cultured on amniotic membrane in DMEM/HamF12 medium for one week. Corneal stem cells and amniotic membrane were transplanted on the limbal and scleral area of the rabbit model with alkali burn. The corneal changes were observed by a slitlamp everyday, and the corneal pathological changes were examined. RESULTS: Cultured rabbit corneal stem cells continued to proliferate, differentiate and form multiple cell layers on amniotic membrane. After transplantation with cultured stem cells and amniotic membrane, the rabbit epithelium showed corneal phenotype and progressive decrease of vascularity and stromal infiltration in the limbal and peripheral zone. Pathological examination verified that the limbal and peripheral corneal epithelium was composed of multilayer cells, the neo-vascularization was reduced and stromal inflammatory cells were decreased. CONCLUSIONS: Allograft transplantation with cultured limbal stem cells can restore corneal epithelial cell composition, decrease neovascularization, maintain limbal cellular barrier function and provide better condition for keratoplasty later.

Alkalies↗

PubMed2000

[Effects of oral calcium supplementation on blood pressure in population].

OBJECTIVE: To assess the effects of oral intake of calcium lactate tablet on blood pressure and serum levels of sodium, potassium, calcium and phosphors. METHODS: In a rural area with natural population with higher average blood pressure and prevalence of hypertension, and with high salt and low calcium intake in diet in Yu County, Shanxi Province, 112 volunteers aged 30 to 64 years were selected based on a mass screening for hypertension, and randomized into trial and control groups with double blinding, taking calcium lactate tablets (800 mg of calcium daily) and placebo respectively for five weeks. Ninety-eight of them complied with the medical order completely, 39 males and 59 females, and were followed-up for systolic (SBP) and diastolic blood pressure (DBP), and their fasting venous blood specimen and 8-hour nocturnal urine specimens were collected. Twenty-four-hour diet recall was obtained for three consecutive days from all of them. RESULTS: Reduction of 4.7 mm Hg (0.62 kPa) and 2.7 mm Hg (0.36 kPa) in systolic and diastolic blood pressure, respectively in the trial group was observed, as compared with that in control one, with P-values of 0.027 and 0.074, respectively, after 35 days of treatment. The higher their baseline BP level, the greater reduction of their BP after treatment. Urinary excretion of calcium increased and serum level of phosphorus reduced after oral administration of calcium. CONCLUSION: In an area with higher prevalence of hypertension and with high salt and low calcium intake in diet, change in diet composition or supplementation with calcium could reduce their average blood pressure and prevent them from hypertension for those with mild and moderate hypertension and in high risk with higher blood pressure.

Administration, Oral↗

PubMed2000

[Supraglottic horizontal partial laryngectomy].

OBJECTIVE: To evaluate the long-term result of supraglottic horizontal partial laryngectomy. METHODS: Fifty-five patients with supraglottic laryngeal carcinoma were treated surgically by supraglottic horizontal partial laryngectomy from 1986 to 1995. There were 32 males and 23 females with an average age of 56. Eleven cases were staged I, 26 staged II, 11 staged III and 7 staged IV. Closure of the surgical defect begins by covering the thyroid cartilage with mucosa of the medial wall of the pyriform sinus. The outer perichondrium of thyroid cartilage was approximated with the mucosa of laryngeal ventricle. The hyoid cartilage was excised. The base of tongue was sutured to the reserved thyroid cartilage to take the place of epiglottic cartilage. RESULTS: The 3- and 5-year survival rates were 85% (47/55) and 77% (37/48) respectively. The decannulation rate was 96%. Most cases had acquired good speech and swallow function after 8-30 days. Complications included granulation and polyp formation at the base of tongue or at the anterior commissure in 4 cases. CONCLUSIONS: Supraglottic horizontal partial laryngectomy is very effective both in eradicating disease and in preserving laryngeal function.

Adult↗

PubMed2000

[Long-term follow-up result of partial laryngectomy].

OBJECTIVE: To study the long-term follow-up result of partial laryngectomy and reservation of laryngeal function. METHODS: Three hundred and seventy-nine patients who underwent partial laryngectomy from 1986 to 1995 were summarized (male 290 cases, female 89 cases). Among them, 184 cases were supraglottic carcinomas (T1 8 cases, T2 115, T3 48, T4 13, according to UICC in 1992), 192 cases were glottic carcinomas (T1 115, T2 63, T3 13, T4 1), 3 cases were transglottic carcinomas (T2 1, T3 2). In common 8 kinds of operations were performed: 26 cases underwent cordectomy, 138 vertical laryngectomy, 7 frontolateral laryngectomy, 12 horizontal glottic laryngectomy (middle part of the larynx), 58 supraglottic laryngectomy, 95 horizontovertical (3/4) laryngectomy, 24 subtotal laryngectomy with cricoglossoepiglottic anastomosis, 19 near-total laryngectomy with cricoglossal anastomosis (with reservation of unilateral arytenoid cartilage). 193 cases underwent concurrent neck dissection(121 unilateral, 72 bilateral). RESULTS: All cases restored their phonation and overcame aspiration with removing nasal feeding from 7 to 23 days after operations. 362 cases were decannulated from 9 days to 3 months after operations. Another 8 cases were decannulated after a secondary plastic operation. Decannulation rate was 97.6%. The three, five and ten year survival rates were 86.8% (329/379), 81.3% (266/327) and 69.4% (120/173) respectively. CONCLUSION: Partial laryngectomy is a kind of radical operation with reservation of laryngeal function. Mastering indications strictly, correct operation choices, excellent surgical skills and perfect repairing technique are bases of improving life qualities and curative effect.

Adult↗

PubMed2000

[Clinical characteristics of different cordectomy types with potassium titanium phosphate laser].

OBJECTIVE: To study the clinical characteristics of different potassium titanium phosphate(KTP) laser types and surgical the recuperating course of cordectomy under suspension laryngoscope. METHOD: Follow-up observation were applied on 76 patients with cordectomy. Restoration of laryngeal structure and change of the quality of voice were observed and recorded. RESULTS: Type 1, normal laryngeal structure and function were restored postoperatively after 3 months; Type 2, a fold like vocal cord (new vocal cord) appeared 3 months later. Laryngeal structure was basically restored; Type 3, a mucosal fold appeared postoperatively after 6 months in most patients, but it lost motion function. Recurrence time was mainly found 2-4 months. Recurrence rate was 6.7%. Two and 5-year survival rate were 100%. CONCLUSIONS: Cordectomy with KTP laser can result in good effect and less injury. Type 2, 3 can retain thyroarytenoid muscle as much as possible on the basis of radical cure.

Adult↗

PubMed2000

[Study of mechanisms of lightening aspiration and increasing decannulation rate in anastomosis of cricoid cartilage and base of tongue (epiglottis)].

OBJECTIVE: To study laryngopharyngeal anastomosis and fixing methods of super-cricoid laryngectomy with reconstruction of functions in lightening aspiration and increasing decannulation rate. METHODS: Recovering conditions of laryngeal functions in 66 patients who underwent supracricoid laryngectomy and anastomosis of cricoid cartilage and base of tongue (epiglottis) in recent eight years were summarized. Some relevant caliber distances in 21 residual larynges were measured. RESULTS: All cases restored their phonation. In 36 cases that underwent anastomosis of cricoid cartilage and base of tongue, 15 cases without aspiration, 18 with mild aspiration, 3 moderates. Decannulation rate is 94.4%. In 30 cases who underwent anastomosis of cricoid cartilage and base of tongue, 10 with mild aspiration, 17 moderate, 3 serious. All cases overcame aspiration within 3 weeks. 7 cases were cannulated. 3, 5, 10 year survival rates were 80.3%, 74.4%, and 3/7. The longitudinal and transverse calibers of epiglottis were 1.5-2.0 times longer than that of the entrance of cricoid cartilage. After anastomosis of cricoid cartilage and base of tongue (epiglottis), the epiglottis can exactly cover the entrance of cricoid cartilage to prevent aspiration fully and increase decannulation rate. Previously the cricoid cartilage was anatomized and fixed under the hyoid bone. Because some spaces exist between cricoid cartilage, base of tongue and epiglottis, aspiration is likely to occur. That hyoid bone covers the entrance of cricoid cartilage will bring constriction of the new laryngeal orifice and make decannulation difficult. Hyoidectomy and anastomosis of cricoid cartilage and base of tongue (epiglottis) overcame the two shortcomings and had good effects. CONCLUSION: Cricoid-hyoid-anastomosis was the main reason of severe aspiration and low decannulation rate. The ideal methods to lighten aspiration and increase decannulation rate are hyoidectomy and anastomosis of cricoid cartilage and base of tongue (epiglottis).

Adult↗

PubMed1999

A negatively charged region of the skeletal muscle ryanodine receptor is involved in Ca(2+)-dependent regulation of the Ca(2+) release channel.

The ryanodine receptor/Ca(2+) release channels from skeletal (RyR1) and cardiac (RyR2) muscle cells exhibit different inactivation profiles by cytosolic Ca(2+). D3 is one of the divergent regions between RyR1 (amino acids (aa) 1872-1923) and RyR2 (aa 1852-1890) and may contain putative binding site(s) for Ca(2+)-dependent inactivation of RyR. To test this possibility, we have deleted the D3 region from RyR1 (DeltaD3-RyR1), residues 1038-3355 from RyR2 (Delta(1038-3355)-RyR2) and inserted the skeletal D3 into Delta(1038-3355)-RyR2 to generate sD3-RyR2. The channels formed by DeltaD3-RyR1 and Delta(1038-3355)-RyR2 are resistant to inactivation by mM [Ca(2+)], whereas the chimeric sD3-RyR2 channel exhibits significant inactivation at mM [Ca(2+)]. The DeltaD3-RyR1 channel retains its sensitivity to activation by caffeine, but is resistant to inactivation by Mg(2+). The data suggest that the skeletal D3 region is involved in the Ca(2+)-dependent regulation of the RyR1 channel.

Amino Acid Sequence↗

PubMed1999

Functional complementation of the Schizosaccharomyces pombe wis1 mutant by Arabidopsis MEK1 and non-catalytic enhancement by CTR1.

Arabidopsis thaliana MEK1 encodes a MAPKK homolog whose role in plants is currently unknown. High (but not low) expression of MEK1 rescued the Deltawis1 (MAPKK) mutant of the Schizosaccharomyces pombe Win1/Wis4-Wis1-Sty1 stress-activated MAPK pathway. Rescue was dependent upon upstream and downstream components of the pathway, suggesting that MEK1 might function in a homologous MAPK pathway in plants. When MEK1 was expressed at a low level, rescue of Deltawis1 was achieved by co-expressing Arabidopsis CTR1 (a putative MAPKK kinase (MAPKKK)). CTR1 constructs alone did not rescue the pathway, indicating that CTR1 augmented MEK1 function. Further data indicated that this enhancement was not due to CTR1 kinase activity.

Arabidopsis↗

PubMed1999

AML1 (CBFalpha2) cooperates with B cell-specific activating protein (BSAP/PAX5) in activation of the B cell-specific BLK gene promoter.

AML1 plays a critical role during hematopoiesis and chromosomal translocations involving AML1 are commonly associated with different forms of leukemia, including pre-B acute lymphoblastic leukemia. To understand the function of AML1 during B cell differentiation, we analyzed regulatory regions of B cell-specific genes for potential AML1-binding sites and have identified a putative AML1-binding site in the promoter of the B cell-specific tyrosine kinase gene, blk. Gel mobility shift assays and transient transfection assays demonstrate that AML1 binds specifically to this site in the blk promoter and this binding site is important for blk promoter activity. Furthermore, in vitro binding analysis revealed that the AML1 runt DNA-binding domain physically interacts with the paired DNA-binding domain of BSAP, a B cell-specific transcription factor. BSAP has been shown previously to be important for B cell-specific regulation of the blk gene. Physical interaction of AML1 with BSAP correlates with functional cooperativity in transfection studies where AML1 and BSAP synergistically activate blk promoter transcription by more than 50-fold. These results demonstrate physical and functional interactions between AML1 and BSAP and suggest that AML1 is an important factor for regulating a critical B cell-specific gene, blk.

Adaptor Proteins, Signal Transducing↗

PubMed1999

CCAAT/enhancer-binding protein activates the CD14 promoter and mediates transforming growth factor beta signaling in monocyte development.

Transcription factors from the CCAAT/enhancer-binding protein (C/EBP) family play important roles in myeloid cell differentiation. CD14 is a monocyte/macrophage differentiation marker and is strongly up-regulated during monocytic cell differentiation. Here, we report the direct binding of C/EBP to the monocyte-specific promoter of CD14. Transactivation analyses demonstrate that C/EBP family members significantly activate the CD14 promoter. These data indicate that C/EBP is directly involved in the regulation of CD14 gene expression. When myelomonoblastic U937 cells are treated with vitamin D(3) and TGF-beta, they differentiate toward monocytic cells. Using specific antibodies against different C/EBP family members in electrophoretic mobility shift assays and Western blot assays, we have identified a specific increase in the DNA binding and the expression of C/EBPalpha and C/EBPbeta during U937 monocytic cell differentiation, and we found C/EBPalpha and C/EBPbeta bind to the promoter in heterodimer. Furthermore, with stably transfected cell lines, we demonstrate that the C/EBP binding site in the CD14 promoter plays a critical role for mediating TGF-beta signaling in the synergistic activation of CD14 expression by vitamin D(3) and TGF-beta during U937 differentiation. This may indicate that C/EBPs have important functions in the process of TGF-beta signal transduction during monocyte differentiation.

Base Sequence↗

PubMed1999

Distribution and prevalence of hyperpolarization-activated cation channel (HCN) mRNA expression in cardiac tissues.

HCN cation channel mRNA expression was determined in the rabbit heart and neonatal and adult rat ventricle using RNase protection assays. In the rabbit SA node, the dominant HCN transcript is HCN4, representing >81% of the total HCN message. HCN1 is also expressed, representing >18% of the total HCN mRNA. Rabbit Purkinje fibers contained almost equal amounts of HCN1 and HCN4 transcripts with low levels of HCN2, whereas rabbit ventricle contained predominantly HCN2. The SA node contained 25 times the total HCN message of Purkinje fibers and 140 times the total HCN message of ventricle. No reports of hyperpolarization-activated current (If) exist in rabbit Purkinje fibers, and we could not record If in rabbit ventricular myocytes. To investigate the possible role of isoform switching in determining the voltage dependence of If, we determined the prevalence of HCN isoforms in neonatal and adult rat ventricle. We had previously determined the threshold for activation of If to be approximately -70 mV in neonatal rat ventricle and -113 mV in adult rat ventricle. In both neonatal and adult rat ventricle, only HCN2 and HCN4 transcripts are present. The ratio of HCN2 to HCN4 is approximately 5:1 in the neonate and 13:1 in the adult. Taken together, these results suggest that different cardiac regions express different isoforms of the HCN family. The HCN1 and HCN4 isoforms are most closely associated with a depolarized threshold for If activation, whereas the HCN2 isoform is associated with a more negative activation curve.

Animals↗

PubMed1999

Sample size determination for multiple comparison studies treating confidence interval width as random.

Methods for optimal sample size determination are developed using four popular multiple comparison procedures (Scheffe's, Bonferroni's, Tukey's and Dunnett's procedures), where random samples of the same size n are to be selected from k (>/=2) normal populations with common variance sigma2, and where primary interest concerns inferences about a family of L linear contrasts among the k population means. For a simultaneous coverage probability of (1-alpha), the optimal sample size is defined to be the smallest integer value n*m such that, simultaneously for all L confidence intervals, the width of the lth confidence interval will be no greater than tolerance 2deltal (l=1,2,...,L) with tolerance probability at least (1-gamma), treating the pooled sample variance S2p as a random variable. Using Scheffe's procedure as an illustration, comparisons are made to usual sample size methods that incorrectly ignore the stochastic nature of S2p. The latter approach can lead to serious underestimation of required sample sizes and hence to unacceptably low values of the actually tolerance probability (1-gamma'). Our approach guarantees a lower bound of [1-(alpha+gamma)] for the probability that the L confidence intervals will both cover the parametric functions of interest and also be sufficiently narrow. Recommendations are provided regarding the choices among the four multiple comparison procedures for sample size determination and inference-making.

Confidence Intervals↗

PubMed1999

Metabolism of methyl tert-butyl ether and other gasoline ethers in mouse liver microsomes lacking cytochrome P450 2E1.

To reduce the production of pollutants in motor vehicle exhaust, methyl tert-butyl ether (MTBE) and other ethers such as ethyl tert-butyl ether (ETBE) and tert-amyl methyl ether (TAME) are added to gasoline as oxygenates for more complete combustion. Metabolism of these gasoline ethers is catalyzed by cytochrome P450 (P450) enzymes. P450 2E1, which metabolizes diethyl ether, was suggested to be an enzyme involved. The present study used 2E1 knock-out mice (2E1-/-) to assess the contribution of 2E1 to the metabolism of MTBE, ETBE and TAME. Liver microsomes prepared from the 2E1 knock-out mice lacked 2E1 activity (assayed as N-nitrosodimethylamine demethylation), but were still active in metabolizing all three gasoline ethers. The levels of ether-metabolizing activity (nmol/min per mg) in the liver microsomes from 7 week old female 2E1 knock-out mice were 0.54+/-0.17 for MTBE, 0.51+/-0.24 for ETBE and 1.14+/-0.25 for TAME at a 1 mM substrate concentration. These activity levels were not significantly different from those of the sex- and age-matched C57BL/6N and 129/Sv mice, which are the parental lineage strains of the 2E1 knock-out mice and are both 2E1+/+. Our results clearly demonstrate that 2E1 plays a negligible role in the metabolism of MTBE, ETBE and TAME in mouse livers.

Aging↗

PubMed1999

Identification of individuals at high risk for head and neck carcinogenesis using chromosome aneuploidy detected by fluorescence in situ hybridization.

To visualize the accumulation of chromosome abnormalities in head and neck squamous cell carcinomas (HNSCC) and investigate the extension of the abnormal field, we applied the fluorescence in situ hybridization (FISH) technique to tumor cells and cells collected from a large extension of clinically normal buccal mucosa distant from the tumor in 10 patients. DNA probes specific for 14 human chromosomes (1, 2, 3, 6, 7, 8, 9, 10, 11, 12, 15, 17, X, and Y) were used in dual-target, dual-color FISH assays. Control specimens were collected from oral mucosa of 10 healthy non-smokers, in order to define the tolerance limits for abnormalities, and from 10 healthy smokers. Extensive aneuploidy was detected in most of tumor specimens, more frequently represented by chromosome gains than losses. Interestingly, the clinically normal distant oral regions displayed chromosomal aneuploidies in seven out of the 10 patients tested. These findings support the occurrence of field cancerization in HNSCC. In addition, interphase FISH is demonstrated as an effective technique for detecting chromosome aneuploidy associated with malignancy and a potential tool for non-invasive screening of individuals at high-risk for HNSCC.

Adult↗

PubMed1999

Interaction between protein kinase C and sphingomyelin/cholesterol.

Physical characteristics of binding of protein kinase C with sphingomyelin/cholesterol lipid bilayers were analysed using three complementary approaches: acrylodan fluorescence, fluorescence energy transfer and quenching of tryptophan fluorescence. It was demonstrated that sphingomyelin/cholesterol lipid membranes were available for protein kinase C binding. The intensity of the binding was dependent on the sphingomyelin content. The results of quenching of intrinsic tryptophan fluorescence showed that the enzyme molecule penetrated the sphingomyelin/cholesterol lipid bilayer to the C-16 position of labeled fatty acid probes. Our results also showed sphingomyelin itself restrains protein kinase C activity. A possible explanation for our results is that caveolae function as signaling storage devices.

Cholesterol↗

PubMed1999

The effect of one injection of Depo-Provera on the human vaginal epithelium and cervical ectopy.

Two studies in rhesus monkeys have shown that progesterone implants, Depo-Provera and Norplant, were associated with vaginal thinning. Progesterone implants have also been associated with an increased risk of simian immunodeficiency virus (SIV) acquisition. This study in 16 women was done to assess vaginal epithelial thickness and number of cell layers from biopsies taken in the untreated follicular and luteal phases, and at 1 month and 3 months after administration of Depo-Provera. There was no significant change over time in either parameter from biopsies obtained in the luteal phase compared with those at either time after Depo-Provera administration. There was also no change in the mean number of Langerhans cells in vaginal wall specimens and no change in cervical ectopy. It appears that women do not respond to exogenous progestins with the dramatic vaginal thinning seen in rhesus monkeys.

Adult↗

PubMed1999

Analysis of redox regulation of cytochrome c-induced apoptosis in a cell-free system.

In this study, we investigated the importance of redox and Bcl-2 status on cytochrome c-mediated apoptosis. Two mouse lymphoma cell lines, LYas and LYar that express Bcl-2 protein at different levels, were used to reconstitute a cell-free system. Cytoplasmic extracts made from apoptosis-sensitive LYas cells 2.5 h after exposure to 5 Gy gamma-radiation were able to induce apoptosis in isolated nuclei, whereas extracts made from LYas cells at time points earlier than 2. 5 h, or from Bcl-2-overexpressing, apoptosis-resistant LYar cells at all time points after irradiation were inactive. Apoptotic activity was restored to inactive extracts by the addition of oxidized but not reduced cytochrome c. Cytochrome c reductase was able to inhibit apoptosis in extracts made from LYas cells 2.5 h after irradiation and LYar extracts activated by addition of oxidized cytochrome c. Antioxidants, but not oxidant defensive enzymes, blocked apoptosis implying that antioxidants might alter the redox state of factors important in mediating apoptosis. These findings confirm the importance of cellular redox state during apoptosis and are consistent with a role for Bcl-2 in regulating this redox state.

Animals↗

PubMed1999

Electronic transmission properties in a mesoscopic necklace with inhomogeneous magnetic flux.

The electronic transmission properties and the energy spectrum of a mesoscopic necklace with inhomogeneous flux is calculated. We found interesting transmission behavior that is quite different from the case with homogenous flux. In this model, the transmission depends on both the modulation mode and the amplitude of the flux. The electronic transmission properties can be explained from the energy spectrum of the system.

Journal Article↗