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Biomedical subjects

Q Fan

Publications and source records attributed to Q Fan.

At least 73 records · Page 4Linked to original sources
PubMed1995

Stability against temperature and external agents of vesicles composed of archael bolaform lipids and egg PC.

The bolaform lipid PLE extracted from the thermophilic archaeon Sulfolobus solfataricus and its mixtures with egg phosphatidyl-choline (egg PC) have been used to prepare sonicated vesicles. The leakage of entrapped calcein was continuously monitored by fluorescence dequenching. The half times of leakage have been used to compare vesicle stability under different conditions of temperature, lipid composition and presence of destabilizing agents like Ca2+ ions and poly(ethylene glycol) (PEG). It has been found that leakage is primarily modulated by the monopolar/bipolar lipid ratio. In particular, the half time of leakage for vesicles formed from a mixture of the polar lipid extract (PLE) and egg PC is characterized by a maximum at about 1:2 molar ratio. The free energy of mixing has been evaluated from pressure-area isotherms on monolayers at the air/water interface. The results indicate a non monotonous behaviour of the excess free energy of mixing as a function of the molar ratio and the occurrence of a minimum at a fixed molar ratio. The possible formation of a complex is discussed and compared with previous calorimetric measurements on similar compounds.

Calcium↗
PubMed1995

Meiosis-specific double-strand DNA breaks at the HIS4 recombination hot spot in the yeast Saccharomyces cerevisiae: control in cis and trans.

The region of Saccharomyces cerevisiae chromosome III located between the 5' end of the HIS4 gene and the 3' end of the adjacent BIK1 gene has a very high level of meiotic recombination. In wild-type strains, a meiosis-specific double-strand DNA break occurs in the hot spot region. This break is absent in strains in which the transcription factors Rap1p, Bas1p, and Bas2p cannot bind to the region upstream of HIS4. In strains with levels of recombination that are higher than those of the wild type, the break is found at elevated levels. The linear relationship between hot spot activity and the frequency of double-strand DNA breaks suggests that these lesions are responsible for initiating recombination at the HIS4 recombination hot spot.

Chromosome Aberrations↗
PubMed1995

[Amplification of proto-oncogenes C-myc, C-N-ras, C-Ki-ras, C-erbB2 in ovarian carcinoma].

OBJECTIVE: To observe the amplification rate of C-myc, C-N-ras, C-Ki-ras, C-erbB2 in human ovarian carcinoma. METHODS: Southern blot hybridization of DNA was employed, pathological diagnosis was made from fresh tissues. The beta-globin gene was used as an internal control. RESULTS: The amplification rate of C-myc, C-N-ras, C-Ki-ras and C-erbB2 in ovarian carcinoma was 50%, 44%, 31% and 25% respectively. The amplification rates of C-myc, C-erbB2 in stage III and IV were all significantly greater than that in stage I (P < 0.01). The amplification rate of C-N-ras in stage I was also significantly greater than that in stage III (P < 0.01). The amplification rate of C-Ki-ras in stage I was significantly greater than that in stage III or IV (P < 0.01). CONCLUSIONS: The amplification of C-Ki-ras and C-N-ras took place chiefly in cases of the early stages and in cases with good differentiation. The amplification of C-N-ras was also found in cases of advanced stages. The amplifications of C-myc and C-erbB2 were chiefly found in cases above stage III and in cases with poor differentiation, 83% of the patients who died were found to have amplifications of more than 2 proto-oncogenes, with the amplification of C-erbB2 involved in all of them.

Blotting, Southern↗
PubMed1995

A specific protein found in human senescent fibroblasts.

The limited potential for proliferation of human fibroblasts in culture represents cell level senescence. Aging is a programmed process under genetic control, and at certain stage of the life-span of animal cells, some genes start to express. Studying the biomarkers of senescent cells is important to understanding the basic mechanism of aging which may be relevant to the normal cell growth control and tumor biology. A protein with 72,000 Dalton molecular weight was detected by the hybridoma method in our laboratory. The protein shows specificity to senescent or presenescent cells of several cell lines, including WI-38, K.D., U2OS, etc.

Animals↗
PubMed1995

Amplifications of proto-oncogenes in ovarian carcinoma.

Thirty-two cases of ovarian carcinoma, two of normal ovaries, four of benign epithelial ovarian tumor, and three of borderline epithelial ovarian tumor were studied using Southern blot hybridization of DNA. In 15 of the 32 cases of ovarian carcinoma, peripheral lymphocytes were also studied. The amplification rate of C-myc, C-N-ras, C-Ki-ras and C-erbB-2 in ovarian carcinoma were 50%, 44%, 31% and 25% respectively. The amplification of C-Ki-ras and C-N-ras took place chiefly in cases of early stage and those of good differentiation. The amplification of C-N-ras was also found in cases of advanced stage. The amplifications of C-myc and C-erbB-2 were chiefly found in cases above stage III and those of poor differentiation. A total of 83% of the patients who died were found to have amplifications of more than 2 proto-oncogenes, with which the amplification of C-erbB-2 was involved.

Adenocarcinoma, Clear Cell↗
PubMed1995

[CF/5-FU-DDP therapy for esophageal carcinoma].

From March 1992 to May 1994, 105 patients with esophageal carcinoma patients were treated with CF/5-Fu-DDP (group A, n = 40) or 5-Fu-DDP (group B, n = 65) protocol. The response rate (CR+PR) was 80% in group A and 60% in group B. (P < 0.01) Induction chemotherapy was followed by surgery or radiation therapy. The incidence of nausea, vomiting, cardiotoxicity and leukopenina was higher in group A than in group B. Buccal mucositis, diarrhea, abdomenal pain and skin pigmentation were noted only in group A. However, the toxic effects were tolerable. The results suggest that the CF/5-Fu-DDP regimen is more effective than 5-Fu-DDP regimen and may be one of the best chemotherapy regimens for the treatment of esophageal carcinoma.

Adult↗
PubMed1995

[Preparation of 125I-F(ab')2-DNR-liposomes and radioimmunoassay of their specific conjugating ability].

The F(ab')2-DNR-liposomes were prepared using F(ab')2 obtained from digested monoclonal antibody against human white cells HI30 (CD45). Their affinity constant for peripheral blood mononuclear cells was determined by radioimmunoassay. Ka = 2.0 x 10(9). A good specific conjugation ability was demonstrated. In preparing the immunoliposomes, it was found that F(ab')2 coupled to the smaller liposomes with higher conjugation ratio.

Antibiotics, Antineoplastic↗
PubMed1994

Positive and negative hepatic regulation of the human type II phospholipase A2 gene.

To identify the elements which regulate the liver transcription of the human type II phospholipase A2 gene and its stimulation by interleukin 6, the 5' flanking region from -1614 to +806 and several 3' and 5' deleted fragments have been analyzed in CAT assays. Negative regulatory elements have been located in the regions -1614 to -326 and +20 to +806. The fragment -326 to +20 contains the main elements required for the transcription as well as for the stimulation by interleukin 6. Footprinting assays have been performed on this region and showed four protected elements, A [-35;-6], B [-125;-86], C [-209;-176], and D [-247;-211]. Deletion of element D enhanced the transcription of the reporter gene 10.5-fold compared to the [-326;+20]-CAT construct. Further deletions up to position -87 which removed both the elements B and C or the substitution of element C by a nonspecific sequence lowered the promoter activity to 23% and 70% of the control, respectively. These results indicate that element C binds positive regulatory factors and element D binds a negative regulatory factor. Furthermore, stimulation by interleukin 6 is lost when element C is substituted or deleted. As shown by the footprinting and band shift assays, the transcription factors C/EBP alpha and C/EBP beta can bind to elements C and D but the dissociation constant (Kd) of C/EBP alpha is 10 times lower for element C (0.6 nM) than for element D (5.8 nM). Band shift experiments using rat liver nuclear extracts showed that element C formed four heat stable complexes, some of which could be supershifted by anti C/EBP alpha antibodies. The binding of C/EBP factors to element C was confirmed by competition with previously described oligonucleotide and nucleotide substitution of element C. Band shift experiments using rat liver nuclear extracts showed that element D formed one major DNA-protein complex. This complex could be competed out by oligonucleotides containing a cAMP responsive element (CRE) but not by oligonucleotides containing the binding site of C/EBP. However, anti-CREB antibodies did not supershift this complex. Methylation interference experiments showed the involvement of a G nucleotide upstream to the sequence homologous to CRE in the binding of the hepatic nuclear factors.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1994

[Management of vessel defect in digit replantation].

Many severed digits are complicated with vessel defects and make replantation more difficult. Based on experimental study, we have repaired vessel defect in 207 cases (261 digits) by 12 methods. 240 digits (92%) survived. Experimental and clinical procedure, treatment of choice and related problems are described.

Adolescent↗
PubMed1994

[Application of the thoraco-umbilical flap in emergent repair of large defect of limbs].

We have repaired larger detect of limbs after emergent debridement using the thoraco-umbilical flap on 13 cases, 6 of which were vascular island flaps, 7 were free flaps. The size of the flaps was 10 cm x 26 cm to 12 cm x 42 cm. All the flaps survived completely. The advantages of the flap are: (1) the pedicle of the flap is long and has a large diameter, (2) the flap can be made quite long so as to cover the whole ulna or tibia, (3) the flap can be used to repair bony defect by carrying a rib as an osteocutaneous flap.

Accidents, Traffic↗
PubMed1993

Decreased vasoactive intestinal polypeptide-immunoreactivity of parasympathetic neurons and target innervation following long-term sympathectomy.

Following long-term sympathectomy, parasympathetic neurons show increased expression of some catecholaminergic traits. The objective of this study was to determine if, in addition, expression of vasoactive intestinal polypeptide immunoreactivity (VIP-ir) is suppressed in parasympathetic neurons and a glandular target of the rat. Studies were conducted on the rat pterygopalatine ganglion and meibomian gland; the meibomian gland contains dense innervation that is strongly VIP-ir, and 99% of the VIP-ir neurons projecting to this target reside within the pterygopalatine ganglion. Two months following unilateral superior cervical ganglionectomy on postnatal day 30, DBH-ir fibers normally present within the eyelid were absent and there was a marked reduction in number and staining intensity of VIP-ir fibers within the meibomian gland. The percentage of pterygopalatine ganglion neurons displaying DBH-ir was increased from 43 +/- 4 to 65 +/- 2%. However, the percentage of parasympathetic neurons expressing VIP-ir was decreased from 96 +/- 4% to 76 +/- 1%. We conclude that sympathectomy not only enhances expression of some catecholaminergic traits but also suppresses VIP-ir within pterygopalatine ganglion parasympathetic neurons and meibomian gland target.

Animals↗
PubMed1993

Complement component C4 deficiencies and gene alterations in patients with systemic lupus erythematosus.

Deficiency of complement component C4 is considered playing a role in the genetic predisposition for systemic lupus erythematosus (SLE). The purpose of this study was to characterize the genomic alterations of the C4 and CYP21 genes in 40 caucasoid patients with SLE by C4 allotyping and by RFLP analysis. Nineteen patients (47.5%) carried C4A null alleles and eight patients (20.0%) C4B null alleles. SLE patients had more frequent C4A null alleles (47.5%) than healthy individuals (20%) (chi 2 = 10.75; P < 0.005). The commonest molecular alteration in the patients with C4A null alleles was a large gene deletion affecting both C4A and CYP21A genes. However, among the patients with C4A null alleles, 16.7% persons had no detectable C4A deletion. The non-expression of C4A gene might be due to defects at various levels of gene expression (i.e. transcription and translation). Among the patients with C4B null alleles, 62.5% persons had no detectable gene lesion, whereas 37.5% showed a C4B deletion including both C4B/CYP21A or C4B/CYP21B genes. Duplication of the C4B gene was not rare in SLE patients, as we found 15.0% of the patients with a heterozygous C4B/CY21A gene duplication. The patients typed as having C4B gene homoduplication (B1,1) demonstrated two long C4B loci, whereas heteroduplication (B1,2) displayed two short loci, therefore the type of C4B gene duplication may be related to the gene length. In conclusion, C4 deficiencies observed in 26 of the 40 SLE patients studied were very heterogeneous. In every case, the gene alteration affected both C4 and CYP21 genes.

Alleles↗
PubMed1992

Robust adaptive parameter estimators in arrhythmia detection.

The authors consider the statistical analysis of threshold crossing intervals, as applied to estimation of tachycardia rates from intracavitary electrograms. The authors developed a class of robust algorithms designed to produce minimum variance estimates for tachycardia rates. The authors formulated the algorithms using order statistic filters, and obtained the minimum variance unbiased order statistic estimator. The potential gain in efficiency achieved by this approach is demonstrated via a representative example. The results indicated that the order statistics operator can produce dramatic reductions for typical errors in error variance as compared to linear estimators.

Algorithms↗
PubMed1992

[The influence of acupuncture on interleukin 2 interferon-natural killer cell regulatory network of kidney-deficiency mice].

The influence of acupuncture on IL2-IFN-NKC regulatory network was investigated, experiments were performed on kidney-deficiency mice received the treatments of acupuncture of "Zusanli" point. The results showed that the interleukin: (IL:), natural killer cell (NKC) activity and interferon (IFN) from the kidney-deficiency mice were lower than that from the normal mice. Acupuncture increased the levels of all the IL2 and NKC activity, acupuncture promoted Newcastle disease virus (NDV) inducing the IFN of kidney-deficiency mice, but also induced the IFN directly. The results suggests that acupuncture could make positive adjustment to IL2-IFN-NKC regulatory network. It provided new theoretical basis for the principles of acupuncture theory on IL2-IFN-NKC regulatory network put forward in recent years.

Acupuncture Therapy↗
PubMed1992

[Mutagenesis study of ethylmethane sulfonate with shuttle vector plasmid pZ189].

Shuttle vector plasmid pZ189 was used as a molecular tool and the SupF inserted in the plasmid was worked as a target gene for mutagenesis study. The host cells (E. coli MBM 7070) with pZ189 were treated with ethylmethane sulfonate (EMS) and plated on the selective media containing X-gal (5-bromo-4-chloro-3-indolyl-beta-D-galactoside) and IPTG (isopropyl-beta-D-thiogalactoside). The SupF and the LacZ amber mutant carried by the host cells complemented each other and thus made the colonies blue on the selective media. However the colonies derived from the SupF mutants changed the colour from blue to white. The mutant frequencies in a series of experiments with different concentrations of EMS were estimated. Furthermore, the DNA isolated from 5 SupF mutants was digested with restruiction enzyme Hha I. It suggests that the 214 bp Hha I fragments containing mutant SupF could be distinguished from their wild type counterparts by temperature-gradient gel electrophoresis under optimal conditions.

Electrophoresis, Polyacrylamide Gel↗
PubMed1990

Gossypol-induced alterations of aminophospholipid composition in human sperm.

Gossypol-induced alterations of aminophospholipid composition in human sperm were observed and the effects of some factors on these alterations were investigated. The alterations of aminophospholipid composition of human sperm induced by gossypol included a progressive decrease in the levels of phosphatidylethanolamine (PE) and phosphatidylserine (PS) when gossypol concentrations ranged from 5-500 mumol/L, and a progressive increase in the level of (LPE) at lower gossypol concentrations (5-50 mumol/L). The conversion of PE into lysophosphatidylethanolamine (LPE) was strongly enhanced by Ca2+ and inhibited by 0.5 mmol/L EDTA, while PMSF, NEM, iodoacetamide and Zn2+ had no effect. This conversion was weaker in sperm with stripped surface proteins than in normal sperm. In addition, three surface proteins (MW 80, 60 and 40 kD) were fixed on the plasma membrane by gossypol treatment. The significance of gossypol action and the possibility that sperm PLA2, PE and some surface proteins might play an important role in the physiological acrosome reaction of human sperm, as well as in oocyte penetration, are discussed.

Gossypol↗
PubMed1986

Effects of hydrocortisone on carbohydrase concentrations, de novo synthesis and turnover patterns in immature rat intestine.

Hydrocortisone administration to infant rats enhanced cellobiase and maltase activities and induced precocious expression of sucrase and trehalase activities along the length of the small intestine. These activity changes reflected proportional concentration increases in the enzymes lactase (EC 3.2.1.23), maltase/glucoamylase (EC 3.2.1.20) and sucrase-isomaltase (EC 3.2.1.48/10). Administration of an equivalent tracer dose of [3H]leucine (by body weight) to control and hydrocortisone-treated infant rats resulted in greater accumulation of label in the carbohydrase pools of the treated rats, suggesting their increased de novo synthesis. The increased concentrations of lactase and maltase/glucoamylase induced by exogenous hydrocortisone were matched by the presence of corresponding greater amounts of label in their brush border pools. Accumulation of label in each of the lactase, maltase/glucoamylase and sucrase-isomaltase pools was generally similar in the hydrocortisone-treated rats, suggesting equivalent stimulation of their synthesis as a group by the humoral agent. The turnover rates of the carbohydrases as a group were found to be similar and did not appear to differ in control and hydrocortisone-treated rats. Total protein synthesis rates were slightly greater in the intestine of the hydrocortisone-treated group of rats.

Aging↗