Search PubMed⌕ Search

Biomedical subjects

C Lu

Publications and source records attributed to C Lu.

At least 199 records · Page 11Linked to original sources
PubMed1996

Volume shifts, unfolding and rolling of haustra in the isolated guinea pig caecum.

The large intestine extracts water from chyme and compacts chyme into faecal conglomerates; it is unclear what role the special pockets known as colonic haustra have in these events. Here we monitored the movements of haustra in isolated preparations of guinea pig caecum using videocamera and ultrasound and related them to contractions of muscle flaps and movements of glass beads in haustral pockets. We found that in partially filled caecal loops localized contractions of taeniae shift volume back and forth between adjacent haustra; volume unfolds haustral walls in a characteristic sweep with sequential intrahaustral folds popping out; cyclic contractions and relaxations of the fold then produce the caterpillar-like movement known as haustral rolling; ultrasound showed that haustral rolling made the haustral flow channel narrower and longer as haustral folds increase their height from 7.5 +/- 1.5 mm to 16 +/- 4 mm and their distance from 4.1 +/- 0.2 mm to 7.9 +/- 0.3 mm; luminal contents were alternatively shaken off the haustral wall, whirled around the lumen or left to settle. We also suspended the row of haustra between two taeniae inside a frame and attached flaps of taeniae and haustral folds to strain gauges to record their mechanical activity; both taeniae and haustral folds produced an undulating baseline tension; during rolling, folds produced phasic contractions at 17 +/- 2 cycles min-1 which propagated distally across haustral septa; rolling constantly shuffled around glass beads placed inside the haustra. When we stimulated the intramural nerves to the caecum through bipolar electrodes, all contractile activity was temporarily inhibited and haustral septa flattened; a rebound contraction then propagated aborally from the caecal pole and swept the glass beads ahead of it. Thus, tonic contractions of taeniae shift caecal contents back and forth across haustral septa; expansion of haustra triggers haustral rolling which shuffles contents; both these movements produce local flow within and between haustra which might enhance the separation of solid and liquid colonic contents.

Animals↗
PubMed1996

Image reconstruction with acoustic measurement using distorted Born iteration method.

The distorted Born iterative method (DBIM) is applied to solve electromagnetics and ultrasonics inverse scattering problems. First, we use the DBIM to process the data, which are the scattered fields from two-dimensional cylinders with arbitrary cross section. From this simulation, we confirmed that the first-order Born approximation can be applied to larger objects as long as the phase change of a wave passing through the object due to its presence is smaller than a limit. Then we applied DBIM to process the ultrasonic measurement data. Images for a balloon and an egg that are immersed in water have been reconstructed and compared with those from the first-order diffraction tomography (DT).

Humans↗
PubMed1996

[A PCR marker-based selection for resistance to bacterial blight in rice].

Molecular marker-based selection in plant breeding requires not only suitable molecular markers closely linked to the known genes, but a simple, economic and reliable analyzing technique. We report here a useful PCR marker for genetic diagnostics in breeding for resistance to rice bacterial blight. Xa21 is a newly found gene of rice which confers resistance to bacterial blight caused by Xanthomonas oryzae pv. oryzae. We produced two F2 populations between one resistant line IRBB21 containing Xa21 and two susceptible varieties, respectively. One PCR marker, PB78, detected polymorphism between the susceptible varieties and the resistant line. Cosegregation between Xa21 and PB78 was studied in the two F2 populations. The results showed that Xa21 was closely linked to the molecular marker, the crossing over value was 2.48%. Marker-based selection revealed that 100% of the plants with homozygous resistant genotype of PB78 showed resistance to bacterial blight. The available approaches detecting molecular markers in plant breeding are also discussed.

Base Sequence↗
PubMed1996

Stable expression of anti-HPV 16 E7-ribozyme in CV-1 cell lines.

The HPV16 (human papilloma virus type 16) E7 gene product, an oncoprotein, has been considered to be involved in the pathogenesis of anogenital cancer, particularly of cervical cancer. In order to evaluate the effect of suppression of the expression of the E7 gene in CV-1 cells by ribozyme, Rz523 with a transacting ribozyme targeted to the E7 RNA and two processing ribozyme genes at the 5' and 3' flank was cloned into the eukaryotic expression plasmid pREP9 under the control of RSV-LTR promoter. The resultant plasmid pRSV-Rz523 was transfected into CV-1 cells by calcium phosphate coprecipitation. The expression of the ribozyme in G418-resistant cells was detected by dot-blot hybridization. Ribozymes stably expressed in the CV-1 cells were at a level of 9.0 pmol per 10(6) cells, in which the active ribozyme molecules were more than 50 fmol per 10(6) cells. The result of RNase protection assay showed that the steady-state level of the E7 RNA fragment in CV-1 cell lines was significantly reduced by about 90% in ribozyme-expressing cells. In contrast, the antisense control plasmid pRSV-AE7 only exhibited about 20%. This result implicated the possibility of reversing the malignant phenotype of cervical cancer by means of suppressing the expression of the E7 gene with ribozyme.

Cell Line↗
PubMed1996

PCR analysis of half-seeds of cereal crops and its application in marker-assisted selection and breeding.

A simple and rapid PCR method was adapted to DNA analysis of cereal seeds. Half-seeds of rice, wheat, and maize were treated with an extraction buffer and the resulting supernatants were used in PCR and RAPD reactions. PCR products amplified from the half-seed DNA extracts were identical with that from leaf tissue DNA extracts when the same specific primers were used in PCR reactions. The remaining half-seeds with embryos could still germinate normally. The half-seed PCR analysis was applied to the identification of resistant genotypes of rice bacterial blight, and it was proved effective in plant breeding and genetic studies.

Breeding↗
PubMed1996

[A study on acute multiple sclerosis].

With the purpose of investigating the clinicopathological changes and the criterion for differential diagnosis, ten cases of Acute multiple sclerosis (AMS) were analysed. The data suggested that its clinical course was an acute neurologic event characterized by psychic syndrome, paralysis and incontinence of bowel movement and urination. Pathologically, the demyelination lesion consisted of three patterns, i.e.: vascullar or spongy lesions, shadow plaques and liquefaction or necrosis. One of the above forms could exist individually or coexist with the others. The accurate diagnosis was made only after autopsy. Criterion for the differential diagnosis between AMS and ADEM were discussed.

Acute Disease↗
PubMed1996

[Purification and characterization of S-layer protein from Aeromonas hydrophila].

The regular surface protein array (S-layer) present on Aeromonas hydrophila J-1 was composed of a single species of protein of apparent molecular weight 51500. This protein was extracted from whole cells by treatment with 0.2 mol/L glycine hydrocholoide (pH4.0). The protein was purified by Sephadex G-200 gel filtration chromatography and an ion exchange chromatography on DEAE-cellulose. Amino acid composition analysis showed that the protein contained 36.8% hydrophobic amino acids. But the protein did not confer hydrophobicity to the cell surface when present as an intact S-layer by salt aggregation test. ELISA and immunoblotting with two different polyclonal antisera against surface exposed-(PM) and non-surface-exposed epitopes (PR) of the protein revealed that the sensitivity of PM was higher than that of PR. Antigenic diversity of the S-layer proteins from 20 bacterial samples was analysed by ELISA with PM and PF1 (polyclonal antiserum against Aeromonas hydrophila TF7 S-layer protein). The S-layer proteins were distinguishable from the extracellular toxin of the homogeneous strains in antigenic and biochemical characterization and the S-layer proteins were one of the main protective antigens.

Aeromonas hydrophila↗
PubMed1996

[Effects of preoperative transcatheter hepatic arterial chemoembolization (TAE) on the prognosis of patients with hepatic carcinoma undergoing tumor resection].

This study consists of 77 hepatocellular carcinoma patients. Twenty-six (Group A) received preoperative TAE and 51 did not (Group B). Group A and B were further divided into two subgroups according to their tumor size i.e. Group A1 and B1 (tumor size 3-8 cm); Group A2 and B2 (tumor size > 8 cm). The 1-, 2-, 3-year disease free survival rates were 50.0%, 33.3%, 16.6% for Group A1 and 72.7%, 54.2%, 39.7% for Group B1; 75.0%, 56.2%, 45.0% for Group A2 and 38.9%, 32.4%, 10.8% for Group B2 respectively. The 1-, 3-, 5-years survival rates were 85.7%, 31.2%, 0 for Group A1 and 84.8%, 58.7%, 27.9% for Group B1; 91.6%, 82.5%, 53.0% for Group A2 and 77.8%, 30.1%, 0 for Group B2 respectively. There were significant differences between Group A2 and B2 both in disease free survival rate and 5-year survival rate (P < 0.05). The results also demonstrated that the preoperative TAE did worsen the prognosis of patients with tumor size between 3-8 cm (Group A1) with disease free survival rate and 5-year survival rate shorter than that of Group A2.

Antineoplastic Agents↗
PubMed1996

Analysis and significance of the malignant 'eclipse' during the progression of primary cutaneous human melanomas.

Why is it that primary melanomas which are less than 0.76 mm in thickness are almost always curable by surgery whereas thicker lesions are associated with a worse prognosis? Put in another way, why is it that such small increases in tumor thickness beyond 0.76 mm are often associated with the eventual formation of distant metastases and death? Part of the answer lies in the dramatic qualitative changes which can accompany small increases in the size of primary human melanomas. Thus, primary melanomas less than 0.76 mm in thickness usually contain very low proportions of metastatically competent tumor cells, whereas slightly thicker lesions can contain very high proportions of such cells, resulting from a selective growth advantage of the latter in the dermal mesenchyme. This overgrowth process is akin to a 'malignant eclipse' phenomenon (by analogy with a solar eclipse). We have been studying the causes of the malignant eclipse in melanoma, for which there are at least four possibilities: 1) an increase in autocrine, mitogenic growth factors by melanoma cells; 2) a decreased rate of apoptosis in the same population; 3) an acquired resistance to paracrine growth inhibitory factors; and 4) an increased ability to induce an angiogenic response. Evidence exists for all four possibilities. Our experimental approach to studying this problem has relied heavily on the use of cell lines obtained from early stage radial growth phase or vertical growth phase lesions which have a clinical-like inability to grow progressively in nude mice, and variants obtained from such lines which are aggressively tumorigenic. Using such paired lines, and other experimental systems, we have obtained evidence that shows early stage melanoma cell lines may be deficient in inducing angiogenesis, are highly sensitive to the growth inhibitory effects of a plethora of cytokines, including transforming growth factor beta, interleukin-6, and oncostatin M, and are more sensitive to undergoing spontaneous apoptosis in several conditions including when growth in anchor-age-independent, 3-dimensional tissue culture. How this information may impact tumor prognosis and the design and effects of new strategies to treat melanoma, especially antiangiogenesis strategies, is discussed.

Animals↗
PubMed1996

Endogenous interleukin 6 can function as an in vivo growth- stimulatory factor for advanced-stage human melanoma cells.

We have previously shown that a majority of human melanoma cell lines derived from early-stage lesions were growth inhibited by exogenous interleukin 6 (IL-6) in vitro, whereas cell lines from advanced-stage lesions were resistant to such IL-6-induced growth inhibition. Among the resistant melanoma cell lines, 50-60% constitutively produced IL-6, which appeared to function as a growth stimulator in vitro, based on the growth-suppressive effects of antisense oligonucleotides to the IL-6 gene. The present study was primarily aimed at evaluating whether endogenous IL-6 also functions in vivo as a growth modulator for IL-6-producing and -nonproducing melanoma cells. To do so, we first introduced an IL-6 expression vector into IL-6-nonproducing human melanoma cells using WM35, an early-stage (radial growth phase) cell line, the growth of which is normally inhibited by IL-6, and WM983A, an advanced-stage cell line, the growth of which in vitro is not affected by exogenous IL-6. None of the IL-6-producing transfectants showed a significant alteration in tumor growth in nude mice. Next, two IL-6-producing melanoma cell lines, both of which were derived from metastases, MeWo and WM9, and which are growth resistant to exogenously added IL-6, were transfected with an antisense IL-6 expression vector. Several transfectant clones manifested a constitutive decrease in IL-6 gene expression and protein production, and they also gave rise to much smaller tumors with slower growth rates and longer latency periods. However, these IL-6 antisense transfectants were not growth suppressed in in vitro cell cultures, relative to their respective parental controls. Taken together, the results demonstrate that endogenous IL-6 can indeed function as a growth stimulator for human cutaneous melanomas in vivo. This growth-stimulatory or survival mechanism remains to be clarified but may be paracrine rather than autocrine in nature.

Animals↗
PubMed1995

Dipyridamole echocardiography for diagnosis of coexistent coronary artery disease in hypertrophic cardiomyopathy. Echo-Persantine International Cooperative (EPIC) Study Group--Subproject Hypertrophic Cardiomyopathy.

The recognition of coexistent coronary artery disease (CAD) in patients with hypertrophic cardiomyopathy may be difficult by noninvasive testing based upon electrocardiographic changes or perfusion defects. Dipyridamole-stress echocardiography has proved a sensitive and highly specific test for noninvasive diagnosis of CAD in various patient subsets. To establish the feasibility, safety, and diagnostic accuracy of dipyridamole-stress echocardiography in patients with hypertrophic cardiomyopathy, we performed high-dose dipyridamole testing (up to 0.84 mg/kg over 10 minutes) in 88 patients with hypertrophic cardiomyopathy (63 men; mean age +/- SD, 46 +/- 17 years). A subset of 60 patients was referred for coronary angiography independently of test results; CAD was defined as > or = 50% diameter narrowing in at least 1 major coronary vessel. Dipyridamole echocardiography/electrocardiography testing was completed in all patients, with no limiting side effects or adverse reactions. In the subgroup of 60 patients with coronary angiography (14 with and 46 without CAD), chest pain occurred in 18 patients (8 with and 10 without CAD, p = NS); ST-segment depression > or = 2 mm from baseline in 28 (7 with and 21 without CAD, p = NS); and transient dyssynergy in 10 patients (10 with and none without CAD, p < 0.0001). Assuming the transient regional dyssynergy to be the only criterion of positivity, the dipyridamole echocardiography test showed 71% sensitivity, 100% specificity, 100% positive predictive value, and 93% diagnostic accuracy for diagnosis of angiographically assessed CAD. We conclude that high-dose dipyridamole echocardiography testing may be considered a feasible and accurate tool for the noninvasive diagnosis of CAD in patients with hypertrophic cardiomyopathy.

Adult↗
PubMed1995

Complex coronary artery lesion morphology influences results of stress echocardiography.

BACKGROUND: The likelihood of a positive response with dipyridamole stress echocardiography (DSE) is directly related to the extent and severity of angiographically assessed coronary artery disease. Whether coronary lesion morphology--a known predictor of adverse cardiac events--may also modulate stress echo results remains unknown. The objective of our study was to assess the relation between stenosis lesion morphology and stress echocardiographic results. METHODS AND RESULTS: High-dose (up to 0.84 mg/kg over 10 minutes) DSE and coronary angiographic data of 68 in-hospital patients (39 with stable angina, 29 with angina at rest) with nonoccluding, single-vessel disease at angiography and no previous myocardial infarction were analyzed. DSE was performed in all patients within 3 days of coronary angiography. An angiographic lesion was considered complex when irregular borders and/or intraluminal lucencies suggestive of ulcer and/or thrombus were present. According to angiographic lesion morphology, two groups were identified: group 1, with simple coronary lesions, and group 2, with complex coronary lesions. The two groups were matched for number of patients (n = 34 in each group), age (group 1, 59 +/- 9 versus group 2, 59 +/- 10 years, P = NS), and coronary artery stenosis severity by quantitative coronary angiography (group 1, 60 +/- 7% versus group 2, 58 +/- 6% diameter reduction, P = NS). The sensitivity of DSE was lower in patients of group 1 when compared with group 2 (53% versus 85%, P < .001). Among positive DSE, the low-dose (0.56 mg/kg over 4 minutes) positivity was less frequent in group 1 than in group 2 patients (17% versus 62%, P < .01). Exercise ECG was completed in 66 patients, and it was positive (> .1 mV ST-segment shift from baseline) in 20 out of 33 group 1 and in 22 out of 33 group 2 patients (61% versus 67%, P = NS). The peak rate-pressure product tended to be higher in group 1 than in group 2 patients (257 +/- 52 versus 240 +/- 64 mm Hg x beats per minute x 10(2), P = NS). CONCLUSIONS: In patients with single-vessel disease without coronary occlusion or previous myocardial infarction, coronary lesion morphology of the complex type is associated with a higher DSE sensitivity and with a greater prevalence of low-dose, positive responses. Presence of irregular plaque contours, not only plaque geometry, is important in modulating stress responses in the presence of angiographically assessed coronary artery disease.

Aged↗
PubMed1995

Determination of mutational spectrum of the pesticide, captan, with an improved set of Escherichia coli LacZ mutants.

The mutational spectrum of the fungicide, captan, was determined using a set of improved Escherichia coli lacZ mutants. Captan created mutations mostly at dA-dT sites (83%) with only 17% occurring at dG-dC sites. The hydrolysis products of captan do not appear to be mutagenic because samples of captan at different hydrolysis stages showed basically the same mutational spectra: 31% at AT --> CG transversions, 8% of GC --> AT transitions, 2% of GC --> CG transversions, 8% of GC --> TA transversions, 19% of AT --> TA transversions, and 32% of AT --> GC transitions. Prepared solutions of captan lost their mutational activity gradually over time, indicating that the rate of decrease in mutagenicity agreed with the kinetics of captan hydrolysis reported in other studies. Using the change in mutagenicity to predict degradation, the hydrolysis of captan in pH 7.0 buffer was about three times faster than the hydrolysis carried out in pH 4.5 buffer. To our knowledge, this is the first presentation of mutational spectrum of captan.

Base Sequence↗
PubMed1995

Preparation and a structure-function analysis of human ciliary neurotrophic factor.

Ciliary neurotrophic factor (CNTF) is a trophic protein that promotes survival and/or differentiation of a variety of neuronal cell types including sensory, sympathetic, and motor neurons. CNTF, leukemia inhibitory factor (LIF), interleukin-6 (IL-6) and oncostatin M (OSM) share a predicted common helical framework and partially identical receptor components. In this study, we present the preparation and structure--functional analysis of recombinant human CNTF. The human CNTF gene was expressed under the control of the PL promoter in Escherichia coli, and the mutants were constructed by insertion, deletion and site-directed mutagenesis. The recombinant proteins were purified from bacteria via DEAE A-50 and Sephacryl S-200 chromatography, and their survival promoting activities were determined using cultures of embryonic chick dorsal root ganglion (DRG) neurons. Insertion at position 23 with APGL, or at position 79 with PRGA, or substitution of 162L163Q for PIDG resulted in proteins with no neurotrophic activity. However, insertion at position 186 with PRGI did not alter human CNTF activity. Deletion of the carboxy-terminal amino acid 186-200 did not reduce the biological activity, but elimination of the amino acid 162-186 abolished the activity. The mutant substituting of 17 Cys for Ser was found to display a biological activity equivalent to that of the wild type. Our data provided experimental confirmation for the structural prediction of CNTF.

Amino Acid Sequence↗
PubMed1995

Regulation of glibenclamide receptors in cultured chick cardiomyocytes.

We found that the expression of sulphonylurea receptors which control ATP-dependent potassium channels was up-regulated both by a receptor agonist and by potassium channel activators. Sulphonylurea receptors detected on cell membranes of cultured chick cardiomyocytes by [3H]glibenclamide were increased 2.8-fold following growth of the cells for 1-2 days in the presence of 30 nM glibenclamide. [3H]glibenclamide binding was also increased approximately 2-fold following growth of the cells in the presence of the ATP-dependent potassium channel activators, pinacidil, minoxidil and diazoxide, but was diminished to 75% of control following treatment with depolarizing concentrations of KCl.

Animals↗
PubMed1995

Expression of leukemia inhibitory factor and interleukin-11 by human melanoma cell lines: LIF, IL-6, and IL-11 are not coregulated.

Dysregulation in cytokines has been associated with melanomas. For example, loss of growth inhibition in advanced melanomas has been associated with interleukin-6 (IL-6) expression. Because IL-6 belongs to the hematopoietic cytokine family, which includes leukemia inhibitory factor (LIF) and interleukin-11 (IL-11), we examined the possibility of coordinate expression of LIF, IL-6, and IL-11 in three human melanoma cell lines derived from primary lesions (early) and in four lines derived from metastatic tumors (advanced). All lines examined produced at least low levels of LIF and IL-11 mRNA as measured by semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR). By enzyme-linked immunosorbent assay (ELISA), two of three early and three of four advanced lines were found to secrete LIF protein. IL-11 was assayed using growth of the responsive B9/11 cell line, but only one of seven lines made a low but measurable amount of IL-11. Cytokine protein production was not strictly correlated with mRNA abundance, nor was it strongly correlated with tumor staging. Recombinant LIF and IL-11 protein had no effect on the proliferation of any of the seven lines, suggesting that they do not act as autocrine growth factors for these melanomas. Assay of IL-6, IL-11, and LIF protein in conditioned medium from early and advanced melanoma lines gave no evidence of coordinate expression of these cytokines. We conclude that LIF and IL-11 production by melanomas may have some paracrine or endocrine function in the course of melanoma progression.

Base Sequence↗