Biomedical subjects

S Luo

Publications and source records attributed to S Luo.

At least 91 records · Page 5Linked to original sources

PubMed1999

ECG beat detection using filter banks.

We have designed a multirate digital signal processing algorithm to detect heart beats in the electrocardiogram (ECG). The algorithm incorporates a filter bank (FB) which decomposes the ECG into subbands with uniform frequency bandwidths. The FB-based algorithm enables independent time and frequency analysis to be performed on a signal. Features computed from a set of the subbands and a heuristic detection strategy are used to fuse decisions from multiple one-channel beat detection algorithms. The overall beat detection algorithm has a sensitivity of 99.59% and a positive predictivity of 99.56% against the MIT/BIH database. Furthermore this is a real-time algorithm since its beat detection latency is minimal. The FB-based beat detection algorithm also inherently lends itself to a computationally efficient structure since the detection logic operates at the subband rate. The FB-based structure is potentially useful for performing multiple ECG processing tasks using one set of preprocessing filters.

Algorithms↗

PubMed1999

Intracerebroventricular administration of bromocriptine ameliorates the insulin-resistant/glucose-intolerant state in hamsters.

Bromocriptine, a potent dopamine D2 receptor agonist, suppresses lipogenesis and improves glucose intolerance and insulin resistance. Recent evidence suggests that bromocriptine may produce these effects by altering central nervous system (CNS) regulation of metabolism. To determine whether or not the CNS plays a critical role in these bromocriptine-mediated effects on peripheral metabolism, we compared the metabolic responses to bromocriptine when administered peripherally versus centrally in naturally obese and glucose intolerant Syrian hamsters. Male hamsters (BW 194 +/- 5 g) were treated with bromocriptine or vehicle either intraperitoneally (i.p., 800 microgram/animal) or intracerebroventricularly (i.c.v., 1 microgram/animal) daily at 1 h after light onset for 14 days while held on 14-hour daily photoperiods. Glucose tolerance tests (GTTs, 3 g glucose/kg BW) were conducted after treatment. Compared to control animals, bromocriptine i.p. significantly reduced weight gain (11.7 vs. -2.4 g) and the areas under the glucose and insulin GTT curves by 29 and 48%, respectively. Similarly, compared with vehicle-treated controls, bromocriptine i.c.v. at 1 microgram/animal substantially reduced weight gain (8.7 vs. -6.3 g), the areas under the glucose and insulin GTT curves by 31 and 44% respectively, and the basal plasma insulin concentration by 41% (p < 0.05). Furthermore, both treatments significantly improved insulin-mediated suppression of hepatic glucose production during a hyperinsulinemic-euglycemic clamp. Thus, daily administration of bromocriptine at a very low dose i.c.v. replicates the metabolic effects of bromocriptine administered i.p. at a much higher dose. This finding demonstrates for the first time that the CNS is a critical target of bromocriptine's metabolic effects.

Animals↗

PubMed1999

Chronic ventromedial hypothalamic infusion of norepinephrine and serotonin promotes insulin resistance and glucose intolerance.

The ventromedial hypothalamus (VMH) is involved in the regulation of peripheral metabolism. We and others have shown that activities, or extracellular metabolites of norepinephrine (NE) and serotonin (5-HT) are elevated in the VMH of both genetically and seasonally insulin-resistant and glucose-intolerant animals. This study examined whether chronic increases in VMH NE and 5-HT concentration of normal animals might lead to insulin-resistant and glucose-intolerant conditions in hamsters. Euinsulinemic, glucose-tolerant hamsters were infused continuously for 5 weeks into the right VMH with either vehicle, NE (5 or 25 nmol/h), 5-HT (2.5 nmol/h), or NE (5 or 25 nmol/h) plus 5-HT (2.5 nmol/h) through osmotic minipumps. Compared to vehicle, NE (25 nmol/h) significantly increased the glucose total area under the curve (TAUC) by 32% during glucose tolerance tests (GTT) conducted after 5 weeks' infusion. 5-HT alone significantly increased the GTT insulin TAUC (131%) and basal plasma insulin level (116%) but not glucose TAUC. NE (5 nmol/h) plus 5-HT infusion significantly increased insulin TAUC (129%) and basal plasma insulin (120%), whereas NE (25 nmol/h) plus 5-HT infusion significantly increased both the GTT glucose and insulin TAUC (43 and 113%, respectively), as well as basal plasma insulin level (158%), relative to vehicle infusion. Our findings demonstrate for the first time the differential and, more importantly, interactive effects of increased VMH NE and 5-HT in producing hyperinsulinemia, insulin resistance and glucose intolerance.

Animals↗

PubMed1999

Mechanical stress regulation and proliferation of rat mandibular condylar chondrocytes in vitro.

OBJECTIVE: To study the proliferative changes of cultured rat mandibular condylar chondrocytes effected by mechanical stress. METHOD: Flow cytometry (FCM) was used to explore the changes of cellular DNA content and cell cycles of passaged condylar chondrocytes. RESULTS: FCM results indicated that proliferation of cultured rat mandibular condylar chondrocytes decreased with stress duration, with marked differences between the experimental and control groups. CONCLUSION: Within given force duration and force range (0-207 g/an2), proliferation of rat mandibular condylar chondrocytes increased with force magnitude, reaching the maximum 6 hours after application of stress. Cellular proliferation decreased when the chondrocytes were cultured under continuous stress for 24 hours. The mechanism for these proliferation changes requires further study.

Animals↗

PubMed1999

[Transurethral microwave tissue coagulation therapy for carcinoma of urinary bladder: an analysis of 35 patients].

OBJECTIVE: To study the reliability of transurethral microwave tissue coagulation therapy for transitional epithelial carcinoma of the urinary bladder. METHODS: The suitable microwave output was affirmed by studying its coagulation effect on pig and human bladder wall according to histo-morphologic changes: Based on this study, transurethral microwave tissue coagulation of bladder cancer (TUMTCBC) was carried out in 35 patients with bladder carcinoma. Biopies were taken from the microwave irradiated sites after the procedure. All patients were given regular intravesical chemotherapy with mitomycin C after microwave treatment and were followed-up for a mean of 56 months. RESULTS: The treatment was effective in all of the treated patints. The recurrence rate and the tumor-free period in patients treated with TUMTCBC was comparable to those in patients treated with transurethral electric cauterization or partial cystectomy. In 19 cases (54.3%), no recurrence of tumor was found in 5 years. CONCLUSION: TUMTCBC is safe, effective and easy to perform. It may be used for the treatment of both superficial and invasive bladder carcinoma.

Adult↗

PubMed1999

[Study on therapeutic effect of carnitine on hepatic steatosis caused by total parenteral nutrition in rats].

OBJECTIVE: To study the hepatic steatosis-minimizing effects of carnitine supplemented total parenteral nutrition (TPN). METHODS: Eighteen normal Wistar rats and nineteen cirrhotic Wistar rats were randomly divided into three groups, respectively: group A (12), chow and libitum; group B (13), TPN for one week group C (12), TPN with carnitine. Liver functions were tested at the seventh day, and also, the liver was resected for histological studies and lipid content determination. RESULTS: Hepatic lipid content was significantly elevated and hepatic steatosis was noted in group B. Hepatic lipid content and hepatic lipid deposit were significantly lowered when carnitine was added to the TPN solution. CONCLUSIONS: Carnitine can minimize hepatic steatosis caused by TPN.

Animals↗

PubMed1999

[Detection of bcr/abl gene expression on bone marrow cell colonies in chronic myelogenous leukemia by reverse transcriptase-polymerase chain reaction].

The t(9;22) (q34;q11) between abl and bcr genes plays a pivotal role in the diagnosis and pathogenesis of chronic myelogenous leukemia(CML). To explore the bcr/abl fusion mRNA expression on hematopoietic precursors, reverse transcriptase-polymerase chain reaction(RT-PCR) was applied to detect bcr/abl mRNA expression on bone marrow cell colonies. Meanwhile, bcr/abl mRNA expressions on 14- or 28-day colonies using HPP-CFC and CFU-GM semisolid agar culture assay were also determined in 4 cases of confirmed Ph-positive CML by karyotyping analysis. The results showed that the bcr/abl mRNA expressions on 14-day colonies and some 14- or 28-day colonies detected singly were positive at presentation by RT-PCR, in agreement with results by karyotype analysis. Thus, a sensitive and powerful technique was offered for studying gene expression on hematopoietic precursors, diagnosis and therapeutic monitoring of CML. Furthermore, this can be used as an ideal method for revealing molecular mechanisms of pathogenesis of CML and screening anti-CML drugs.

Adult↗

PubMed1999

[The behaviour of rat mandibular condylar cartilage in cell culture].

This study aimed to identify the behaviour of mandibular condylar chondrocytes in vitro. Cells were harvested from the mandibular condyles of 3 week-old S. D. rats. Cell structure, morphology and characteristics were assessed by phase-contrast microscopy, scanning electron microscopy, enzymohistochemistry and immunohistochemistry. The cultured condylar chondrocytes, stellated or spindle-shaped, could grow in several layers and form many cell colonies. They could secret proteoglycans, alkaline phosphatase, type II collagen, et al. The methods of isolation, culture and identification of condylar chondrocytes were presented and discussed, which can be adopted in probing further into the cellular mechanism of functional orthopedics.

Animals↗

PubMed1999

[Mesothelioma in rats following-intrapleural-injection of crocidolite].

In order to investigate the potential of pleural mesothelioma induced by crocidolite, author collected samples from four county areas (Dayao, Yaoan, Muding and Yanyuan) in China. A suspension of 1 ml containing 20 mg crocidolite fiber was injected into the right pleural cavity of each rat in various test groups and UICC crocidolite group, totally 40 mg. The negative control was given saline. The results showed that the incidence of mesothelioma was 56.0%-68.8% (in which the rate of induction in Yanyuan group was the highest), and the survival time of the first case of mesothelioma was 273-347 days in the test groups, the Yanyuan group had shorter latency, and the mean survival days of the rats with mesothelioma for four groups were 560, 490, 593 and 498 days respectively; the shortest mean survival time was that for Yanyuan group. The major histological type of mesothelioma induced by crocidolite was the fibrous type. The degree of differentiation in all mesotheliomas was mainly intermediate and low. The results suggested that when rats were intrapleurally inoculated with samples of crocidolite and saline, an appreciable proportion of animals developed mesothelioma except those of the saline group. Compared with other groups, the Yanyuan group had stronger potential of crocidolite-induced mesothelioma.

Animals↗

PubMed1999

[A radioimmunologic assay of insulin in lateral pterygoid muscle after functional mandibular protrusion in rats].

OBJECTIVE: To investigate the effect of insulin on the lateral pterygoid muscle after functional mandibular protrusion in rats. METHODS: Radioimmunoassay was used to examine the level of insulin in lateral pterygoid muscle quantitatively after functional mandibular protrusion in young growing rats. RESULTS: The amount of insulin in lateral pterygoid muscle in young growing rats enhanced after functional mandibular protrusion. CONCLUSION: Insulin plays an important role in adaptive remodeling of lateral pterygoid muscle after functional mandibular protrusion.

Animals↗

PubMed1999

[Study on mechanical compression regulating the proliferation of rat mandibular condylar chondrocytes in vitro].

OBJECTIVE: To study the proliferative changes of cultured rat mandibular condylar chondrocytes effected by mechanical compression. METHODS: Using flow cytometry(FCM) to explore the changes of cellular DNA content and cell cycles of passaged condylar chondrocytes. RESULTS: During certain force range (0-207 g/cm2), the proliferation of rat mandibular condylar chondrocytes rose, reaching the maximum after 6-hour application of force. The cellular proliferation went down when the chondrocytes were cultured under continuous pressure for 24 hours. CONCLUSION: The proliferation of rat mandibular condylar chondrocytes increase under certain force and certain period of time, but decreased if the applied pressure is beyond the magnitude.

Animals↗

PubMed1999

[Study of the distribution and migration laws of nitroglycerin in energy increasing propellant by size exclusion chromatography].

It is very important to increase the energy of high-nitrogen-content single-base propellant by absorbing nitroglycerin in the case of keeping the advantage of the original propellant. In this paper, the distribution laws and migration laws in the aging of nitroglycerin have been studied by size exclusion chromatography (SEC) after high-nitrogen-content single-base propellant absorbing nitroglycerin. The results show that the distribution of nitroglycerin in high-nitrogen-content sigle-base propellant follows the Gauss distribution. In aging, this distribution changes towards the big variance Gauss distribution. The relationship between migration mass and aging time is y = k1e-k2/t, for external layer k1 = 0.1208 and k2 = 17.229, for inner hole k1 = 0.0348 and k2 = 10.97. The migration velocity constant, K = A0e-E/RT, of nitroglycerin is also given in this article, where A0 = 0.4086 and E0 = 1.6702 kJ/mol for inner hole, A0 = 31.2775 and E0 = 3.5428 kJ/mol for external layer.

English Abstract↗

PubMed1999

[Studies on immune responses in mice to expressed products from CSP gene of Plasmodium falciparum FCC1/HN isolate].

AIM: To construct the eukaryotic expression system with pcDNA3-PfCSP/HeLa for CSP gene of Plasmodium falciparum, and to observe the immune responses in BALB/c mice induced by the expressed proteins. METHODS: The recombinant plasmid pcDNA3-PfCSP was transformed into mammalian cell line of human HeLa cells. The expressed protein was isolated and analyzed by SDS-PAGE and used for immunization of BALB/c mice by subcutaneous, intravenous or intraperitoneal administration, respectively. ELISA, Western blotting, T lymphocyte proliferation test, natural killer cell activity and CD4+ and CD8+ T cells detection were used for observation of the level of humoral and cellular immune responses. RESULTS: Immune sera strongly reacted with the expressed protein. The titer of the antibodies was up to 1:6,400 by ELISA. Western blotting analysis revealed a specific band at 38.3 kDa. The specific proliferative response with immunized BALB/c mice spleen cells was remarkablely higher than that with control ones. The ratio of CD4+ and CD8+ T cells and the NK cell activity were significantly higher in the immunization group than that in the control groups. CONCLUSION: The humoral and cell-mediated immune responses and elevated NKC activity to expressed products with the eukaryotic expression system can specifically be detected in BALB/c mice to generate, indicating that the expressed protein could enhance immune activity in mice.

Animals↗

PubMed1999

[Recombination and cloning of MSP1(19) and PfCMR of Plasmodium falciparum].

AIM: To construct a recombinant plasmid DNA encoding multiantigens of Plasmodium falciparum and to provide the requirements for DNA immunization. METHODS: Two oligonucleotide primers were designed to amplify MSP1(19), the purified PCR products were digested by Sal I + Xba I, and the recombinant plasmid pWR450-1/PfCMR was digested by EcoR I + Sal I to recover PfCMR gene. PfCMR and MSP1(19) gene fragments were linked and recombined with mammalian expression vector pcDNA3. RESULTS: The MSP1(19) gene fragment with about 363 base pairs were specifically amplified by using PCR technique. The positive recombinant pcDNA3-PfCMR-MSP1(19) (named pcDNA3-Pf8) was screened and identified by agarose gel electrophoresis, endonulease digestion and PCR technique, the whole length of Pf8 is 618 bp. CONCLUSION: By specifically amplifying MSP1(19) gene at the C-terminal of MSP1, a recombinant plasmid pcDNA3-Pf8 encoding multiantigens of Plasmodium falciparum was successfully constructed.

Animals↗

PubMed1999

[Cloning and sequencing of the genes coding for the histidine-rich protein II of Plasmodium falciparum].

AIM: To compare and analyze the homology of genes encoding histidine-rich proteinII (HRPII) of different Plasmodium falciparum isolates. METHODS: Using PCR technique, the complete genes coding for HRPII of P. falciparum isolates FCC1/HN and VN isolates were amplified. PCR products were digested by HindIII/BamHI and cloned into plasmid pUC19. The recombinant plasmid HRPII/pUC19 was screened and identified by PCR and restriction analysis. The cloned HRPII genes were sequenced by Sanger's method. RESULTS: HRPII genes of FCC1/HN and VN isolates were successfully amplified and cloned into pUC19. DNA sequencing showed that the coding length of HRPII gene was 1,020 bp without introns in FCC1/HN and VN isolates, however, there were ten points mutations between them. FCC1/HN isolate exhibited 98.8%, 92.2% and 98.7% homology in amino acids with isolates VN, IMTM22, and Itg2, respectively. Though the numbers of repeat sequences were different in four isolates, they had the same hydrophobic leader sequence and a single putative glycosylation site. The secondary structure analysis showed that the main antigenic determinants of four isolates were located on 5' end non-repeat region (amino acids 1-60). CONCLUSION: FCC1/HN isolate was highly homologous in the coding region of HRPII with VN, IMTM22, and Itg2 isolate. Four isolates exhibited similar structural characteristics and antigenic determinants in HRPII.

Amino Acid Sequence↗

PubMed1998

Effect of citrulline for arginine replacement on the structure and turnover of phosphopeptide substrates of protein phosphatase-1.

Phosphorylated and nonphosphorylated forms of a decapeptide corresponding to residues 9 to 18 of glycogen phosphorylase were compared using two-dimensional nuclear magnetic resonance with assignment of both peptides done by the sequential method. Both forms had little secondary structure, but there was evidence for an interaction between arginine-16 and phosphorylated serine at position 14. A change in the chemical shift for the epsilon-nitrogen hydrogen of arginine in position 16 was observed in the spectrum of the phosphorylated peptide and was not evident in a phosphopeptide having citrulline in place of arginine-16. Hydrolysis catalyzed by protein phosphatase-1 was decreased with the citrulline-containing phosphopeptide compared to the arginine-containing phosphopeptide with effects observed on both kcat and Km of the phosphatase reaction. Alkaline phosphatase hydrolyzed these peptides and a di-citrulline peptide equally well. These results are consistent with arginine being favorable in the recognition of substrates by phosphatase-1, possibly recognition as an arginine-phosphoserine complex. As a model study, arginine and two analogs, citrulline and canavanine, were examined for association with inorganic phosphate by nuclear magnetic resonance spectrometry. 31P-NMR measurements showed that arginine and canavanine caused a shift in the phosphate resonance at 20 degreesC. Citrulline caused no change. Changes in chemical shift were measured over the pH range 5-9 with arginine and canavanine both causing a slight decrease in the apparent pKa of inorganic phosphate (DeltapKa approximately 0.15). NaCl, NH4Cl, and guanidine hydrochloride showed little effect on the resonance signal position of inorganic phosphate at pH 6.5, consistent with selectivity for the guanidino group. Temperature (6 degrees, 20 degrees, and 37 degreesC) caused little change in the effect of arginine, but there was some dependency with canavanine, decreasing with temperature. Citrulline caused no change in the chemical shift of phosphate at any temperature. It was concluded that hydrogen bonded complexes were formed between the dianion of phosphate and the protonated form of arginine or canavanine with a bifurcated structure having preference for the omega-hydrogens.

Alkaline Phosphatase↗

PubMed1998

alpha-conotoxin AuIB selectively blocks alpha3 beta4 nicotinic acetylcholine receptors and nicotine-evoked norepinephrine release.

Neuronal nicotinic acetylcholine receptors (nAChRs) with putative alpha3 beta4-subunits have been implicated in the mediation of signaling in various systems, including ganglionic transmission peripherally and nicotine-evoked neurotransmitter release centrally. However, progress in the characterization of these receptors has been hampered by a lack of alpha3 beta4-selective ligands. In this report, we describe the purification and characterization of an alpha3 beta4 nAChR antagonist, alpha-conotoxin AuIB, from the venom of the "court cone," Conus aulicus. We also describe the total chemical synthesis of this and two related peptides that were also isolated from the venom. alpha-Conotoxin AuIB blocks alpha3 beta4 nAChRs expressed in Xenopus oocytes with an IC50 of 0.75 microM, a kon of 1.4 x 10(6) min-1 M-1, a koff of 0.48 min-1, and a Kd of 0.5 microM. Furthermore, alpha-conotoxin AuIB blocks the alpha3 beta4 receptor with >100-fold higher potency than other receptor subunit combinations, including alpha2 beta2, alpha2 beta4, alpha3 beta2, alpha4 beta2, alpha4 beta4, and alpha1 beta1 gamma delta. Thus, AuIB is a novel, selective probe for alpha3 beta4 nAChRs. AuIB (1-5 microM) blocks 20-35% of the nicotine-stimulated norepinephrine release from rat hippocampal synaptosomes, whereas nicotine-evoked dopamine release from striatal synaptosomes is not affected. Conversely, the alpha3 beta2-specific alpha-conotoxin MII (100 nM) blocks 33% of striatal dopamine release but not hippocampal norepinephrine release. This suggests that in the respective systems, alpha3 beta4-containing nAChRs mediate norepinephrine release, whereas alpha3 beta2-containing receptors mediate dopamine release.

Acetylcholine↗

PubMed1998

In situ measurements of ribulose-1,5-bisphosphate carboxylase activity by nuclear magnetic resonance.

High-resolution NMR spectroscopy is demonstrated to be capable of monitoring in situ the carboxylation reaction catalyzed by ribulose-1,5-bisphosphate carboxylase. Specific activities are determined for three enzymes from different sources containing higher plant and photosynthetic bacteria, and they are in agreement with those measured by other methods. Several important features of the reaction have been confirmed at the atomic level. A decrease in activity with time after the reaction started has also been observed for both enzymes with L8S8 and L2 structures from photosynthetic bacteria and higher plants, suggesting that the "fallover" of activity may be a more general phenomenon. 1H spectra obtained with H2O as solvent provide the most efficient quantitative measurement of the reaction product, 3-phosphoglycerate. 31P spectra give essentially the same result as 1H NMR but have the advantage of showing the degree of reaction at any time during the reaction. The incorporated carbon atom is unequivocally identified as the C-1 carbon of 3-phosphoglycerate from the 13C spectrum.

Hydrogen-Ion Concentration↗