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S Chen

Publications and source records attributed to S Chen.

At least 1,153 records · Page 64Linked to original sources
PubMed1994

The detection of HPV DNA, the size of tampon specimens and the menstrual cycle.

OBJECTIVE: To determine if HPV detection or the size of a tampon specimen is affected by the menstrual cycle. MATERIALS: Two hundred and eighty women between 18-35 years of age attending a gynaecology clinic at The Royal Women's Hospital were enrolled. Each woman completed a questionnaire on the risk factors of HPV infection and provided a tampon specimen. Specimens were analysed for the presence of HPV DNA (polymerase chain reaction with the L1 consensus primers) after the pellet volume and number of cells was assessed. RESULTS: The mean age of the 298 women enrolled in this study was 27.0 years (SD 4.5, range 18-35). Ninety two (30.9%) of the tampon specimens were positive for HPV using the L1 consensus primer. The detection of HPV DNA was not associated with the quartiles of the menstrual cycle (p = 0.32). Both the pellet volume and the number of cells from a tampon specimen were greater during the mid cycle, although this was significant for the pellet volume only (p = 0.002 and 0.1 respectively). The pellet volume was not significantly associated with other variables assessed by the questionnaire. The number of cells from a tampon specimen increased with the numbers of life time sexual partners (p = 0.02) and was higher for a single marital status (p = 0.0008). CONCLUSION: The timing of the menstrual cycle effects the size of tampon specimens but not the probability of detecting HPV DNA.

Adolescent↗
PubMed1994

Chronic blood pressure effects of bufalin, a sodium-potassium ATPase inhibitor, in rats.

Endogenous Na+,K(+)-ATPase inhibitors may have a role in the mechanism of low-renin hypertension. Two such compounds have been characterized: ouabain from human plasma and resibufogenin from toad plasma. Previously, we examined the acute effects of ouabain and bufalin (which has the same structure as resibufogenin except for one H+) in normal rats. Bufalin raised blood pressure, but ouabain had little effect. In contrast, given chronically, ouabain substantially increased blood pressure in normal rats and 70% reduced renal mass rats on a salt-free diet. We have now examined the chronic effects of bufalin in rats. Normal rats received 14.8 micrograms/kg per day bufalin or an equimolar dose of ouabain intraperitoneally for 6 weeks; 70% reduced renal mass rats also received 14.8 micrograms/kg per day bufalin. Another group of normal rats received 29.6 micrograms/kg per day bufalin intraperitoneally for 6 weeks. Respective control animals received vehicle. In contrast to ouabain, blood pressure did not increase in normal rats receiving the 14.8 micrograms dose of bufalin. However, normal rats receiving 29.6 micrograms bufalin and 70% reduced renal mass rats receiving 14.8 micrograms bufalin developed significant increases in blood pressure. Increases in blood pressure were associated with decreases in myocardial Na+,K(+)-ATPase activity and correlated with increased plasma Na+,K(+)-ATPase inhibitory activity. Thus, although bufalin is a more potent pressor agent than ouabain when both agents are given acutely, ouabain is at least as potent a vasopressor agent as bufalin when given chronically. Thus, both are pressor agents, more so in the presence of reduced renal mass, when given chronically in the rat.

5'-Nucleotidase↗
PubMed1994

Effect of administration of insulin on streptozotocin-induced diabetic hypertension in rat.

We have reported that streptozotocin-induced insulin-dependent diabetes mellitus in 25% reduced renal mass rats is associated with low-renin, volume-expanded hypertension and that the development of the hypertension can be prevented with insulin. In this study we examined the effect of insulin after the animals had developed sustained hypertension. Normotensive 25% reduced renal mass rats were treated with streptozotocin and, as expected, developed insulin-dependent diabetes mellitus and hypertension. After 4 weeks of sustained hypertension, neutral protamine Hagedorn insulin (6 to 8 IU/d) was administered subcutaneously for 4 weeks. As expected, insulin treatment decreased plasma glucose and increased body weight gain relative to untreated diabetic rats. On the other hand, insulin treatment did not reverse the hypertension and albuminuria. It also did not normalize extracellular fluid volume and plasma renin activity. Furthermore, insulin treatment did not reverse the increase in plasma Na+,K(+)-ATPase inhibitory activity (determined by both radioimmunoassay and bioassay) and the inhibition of myocardial microsomal Na+,K(+)-ATPase activity observed in the untreated diabetic hypertensive rats. 5'-Nucleotidase, a membrane marker, was not different between insulin-treated and untreated diabetic rats. These results show that insulin, given as here described, does not reverse the insulin-dependent diabetes mellitus hypertension in 25% reduced renal mass rats once it is established, perhaps because it does not reverse the albuminuria, volume expansion, increase in endogenous digitalis-like substance, and inhibition of cardiovascular muscle cell Na+,K(+)-ATPase activity.

Animals↗
PubMed1994

More direct evidence for a malonyl-CoA-carnitine palmitoyltransferase I interaction as a key event in pancreatic beta-cell signaling.

We sought to explore the emerging concept that malonyl-CoA generation, with concomitant suppression of mitochondrial carnitine palmitoyltransferase I (CPT I), represents an important component of glucose-stimulated insulin secretion (GSIS) by the pancreatic beta-cell (Prentki M, Vischer S, Glennon MC, Regazzi R, Deeney JT, Corkey BE: Malonyl-CoA and long-chain acyl-CoA esters as metabolic coupling factors in nutrient-induced insulin secretion. J Biol Chem 267:5802-5810, 1992). Accordingly, pancreases from fed rats were perfused with basal (3 mM) followed by high (20 mM) glucose in the absence or presence of 2 mM hydroxycitrate (HC), an inhibitor of ATP-citrate (CIT) lyase (the penultimate step in the glucose-->malonyl-CoA conversion). HC profoundly inhibited GSIS, whereas CIT had no effect. Inclusion of 0.5 mM palmitate in the perfusate significantly enhanced GSIS and completely offset the negative effect of HC. In isolated islets, HC stimulated [1-14C]palmitate oxidation in the presence of basal glucose and markedly obtunded the inhibitory effect of high glucose. Directional changes in 14C incorporation into phospholipids were opposite to those of 14CO2 production. At a concentration of 0.2 mM, 2-bromostearate, 2-bromopalmitate and etomoxir (all CPT I inhibitors) potentiated GSIS by the pancreas and inhibited palmitate oxidation in islets. However, at 0.05 mM, etomoxir did not influence insulin secretion but still caused significant suppression of fatty acid oxidation. The results provide more direct evidence for a pivotal role of malonyl-CoA suppression of CPT I, with attendant elevation of the cytosolic long-chain acyl-CoA concentration, in GSIS from the normal pancreatic beta-cell.(ABSTRACT TRUNCATED AT 250 WORDS)

ATP Citrate (pro-S)-Lyase↗
PubMed1994

Analysis of human hematopoietic stem cell populations.

Purification of human hematopoietic stem cells (HSC) may be useful clinically for preparation of tumor-free grafts to be used for autologous transplantation and as targets for gene therapy. To analyze the phenotype of the human HSC, assays were used that measure the unique properties of stem cells, i.e., their long-term repopulating ability and their multilineage potential. These assays include: (1) an in vitro long-term hematopoietic culture system, using the murine bone marrow stromal cell line SyS1, which supports both B lymphopoiesis and myelopoiesis; (2) fetal human bone grafts implanted in SCID-hu mice, in which maintenance of CD34+ cells and B and myeloid differentiative capacity of candidate stem cell populations may be measured; (3) fetal human thymus grafts in SCID-hu mice, which allow the analysis of in vivo T-cell potential of a candidate stem cell population. Stem cells in adult bone marrow (ABM) or cytokine-mobilized peripheral blood (MPB) are thought to express CD34 but lack expression of markers indicating lineage commitment. This CD34+ Lineage- (Lin-) subpopulation has been isolated by fluorescence-activated cell sorting and tested for activity in the assays described here. CD34+ Lin- cells from both ABM and MPB demonstrated long-term engraftment in the SCID-hu bone model. This CD34+ Lin- population can be subfractionated further using an antibody to Thy-1. The Thy-1+ subset of CD34+Lin- cells is enriched for both long-term culture-initiating cells (LTC-1C) and has the ability to engraft in vivo.

Animals↗
PubMed1994

[Effect of indirect fluorescent antibody test for the diagnosis of amoebiasis].

Indirect fluorescent antibody test (IFAT) was performed by the method of [symbol: see text] (1971) with some slight modifications for the diagnosis of amoebiasis. The antigen used was prepared from 48-hour culture of Entamoeba histolytica (strains G2, G3, and G5) in LAS diphasic medium and only those amoebae clinging the culture were collected. The serum samples or blood drops on filter paper were positive by the improved IFAT in all of the 54 cases of amoebic liver abscess and the positive reactions of most cases were very marked. Of 23 cases of acute amoebic dysentery, 19 were positive, the positive rate being 82.6%. The results also show that 42 cases of other diseases and 40 healthy persons were all negative.

Animals↗
PubMed1994

[Influence of thoracic spinal subarachnoid microinjection of phentolamine on the effect of electroacupuncture].

The influence of thoracic spinal subarachnoid microinjection of Phentolamine (Phen, 200ug/20ul) on the effect of electroacupuncture (EA) at Neiguan (PC 6) was observed in 42 urethan-chloralose anesthetized rabbits. Results showed that: 1) EA of Neiguan (PC 6) could significantly promote recovery of elevated ST-segments and T-waves of electrocardiogram induced by acute myocardial ischemia (AMI). 2) subarachnoid microinjection of phentolamine had no marked influence on recovery of ST-segments and T-waves, but impeded recovery of blood pressure of post-AMI; and 3) subarachnoid microinjection of phentolamine could significantly weaken or eliminate the effect of EA of Neiguan (PC 6) in accelerating recovery of ST-segments and T-waves of post-AMI. It denotes that alpha-receptors of intra-thoracic spinal cord participate in the action of EA of Neiguan (PC 6) in improving AMI, and the upper thoracic segment of the spinal cord is one of the links for connecting Neiguan and the heart.

Animals↗
PubMed1994

[Detection of antibodies against Legionella pneumophila from pleural effusion--a case report of Legionnaire's pneumonia with pleural effusion].

Using TAT and ELISA, 50 samples of pleural effusion and sera from patients infected with non-Legionella pneumophila were detected for antibodies against Legionella pneumophila serogroups 1 and 6, respectively. The average titre and upper limit value (99%, mean + 2.326S) calculated. In addition, a pleural effusion and a serum from a patient with Legionnaire's pneumonia were also detected by TAT and ELISA. The result showed that the titre of this antibody in his pleural effusion was not only over the upper limit, but also higher than that in his serum.

Adolescent↗
PubMed1994

[Influence of electroacupuncture of neiguan (PC 6) on ami-induced changes in electrical activity of dorsal horn neurons].

The electrical activity of the dorsal horn (DH) neurons was recorded extracellularly by glass micro-pipettes in urethane-chloralose anesthetized rabbits to analyze the role of the thoracic segments (T2-T3) of the spinal cord in the integration of information from electroacupuncture (EA) at Neiguan (PC 6) and acute myocardial ischemia (AMI). Results were: 1) after AMI, of 83 DH neurons, 18 displayed a significant excitatory response, 14 an obvious inhibitory reaction and 51 no apparent change; 2) after EA at Neiguan (PC 6), of 10 neurons with AMI-induced excitatory response, the electrical activity of 9 neurons was suppressed and the other 1 still maintained its excitatory state; of 8 neurons with AMI-induced inhibitory response, 7 were relieved from the suppressed state, the other 1 had no change following EA; and 3) the receptive field and the responsive types to somatic stimulation were examined in 83 DH neurons. Results showed that signals from EA at Neiguan (PC 6) and AMI could converge to the DH neurons of T2-T3. It suggests that DH participates in the integrative course of information from EA and AMI and thus it is one of the connective links between Neiguan (PC 6) and the heart.

Acupuncture Points↗
PubMed1994

[Comparative study on three serologic tests for detecting antibodies in cases with bancroftian microfilaremia].

A comparative study was conducted for detecting antibody levels of bancroftian microfilaremia cases by using three serologic tests, IFAT, ELISA and dot-ELISA. A total of 102 serum specimens were collected from bancroftian microfilaremia cases. The positive rate was 89.2% (91/102) with IFAT (serum dilution > or = 1:20), 84.3% (86/102) with ELISA (OD value > or = 0.440) and 89.2% (91/102) with dot-ELISA (serum dilution > or = 1:80), respectively (P > 0.05); while in healthy individuals from non-endemic areas the false positive rate was 0(0/30), 1.8(1/55) and 0(0/54), respectively. The results indicated that there were no statistically significant differences among the three serologic tests. There was no correlation found in this study between microfilaria density and the antibody level. It was also proved that the detection rate of the combined use of either 2 or 3 tests was higher than each of the three tests; the positive rates being 94.1%-98.0%.

Animals↗
PubMed1994

[Morphometric study of motor cortex in acute focal epilepsy rat induced by coriaria lactone].

Twenty adult male Wistar rats were divided randomly into two groups (10 rats for LM, 10 rats for EM). The experimental rats were injected with convulsive dosage 3.8 microliters (19 micrograms) of coriaria lactone (CL) in the left cerebral motor cortex of the fore limb to induce acute focal epilepsy. The control rats were injected with normal saline of the same volume and at the same location. Motor cortex was cut coronally 2 hours after seizure and the layer V was studied morphometrically. Under x400 and x7000, take photos of focus, parafocus areas respectively for morphometric study. The number of neurons and neuroglias of layer V was counted in the LM photos. The number of presynaptic terminals of the neuropil was counted in the x7000 EM photos and the area fraction of each constitute in the neuropil was measured. The positive results demonstrated that the number of neurons and neuroglias in the focus and parafocus areas of the experimental animals was significantly lower than that in the control group, the side injected was lower than the other side and it was the lowest in the focus. The number and area fraction of the presynaptic terminals of the experimental rats at the focus neuropil decreased significantly, but the area fraction of neuroglial components increased significantly. The authors suggest that the convulsive dosage of CL may have toxic effect on some neurons and neuroglias and therefore to decrease the number of both types of cells and the number and area fraction of presynaptic terminals in the neuropil.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1994

Human papillomavirus infection and its relationship to recent and distant sexual partners.

OBJECTIVE: To determine the relation between the detection of genital human papillomavirus (HPV) DNA and the number of new sexual partners in the last year, 1-5 years, and 5-10 years. METHODS: In a cross-sectional study, 298 women collected tampon specimens and completed self-answer questionnaires on the known risk factors for HPV infection, including the number of sexual partners during the last 1, 5, and 10 years. The tampons were analyzed for the presence of HPV DNA by polymerase chain reaction using L1 consensus primers. RESULTS: Ninety-two (30.9%) tampons were positive for HPV DNA. In univariate analysis, the presence of HPV DNA was associated with a younger age, single marital status, a previously abnormal or currently abnormal Papanicolaou smear, and one or more new sexual partners in the last year, 1-5 years, and 5-10 years. The presence of HPV DNA was not associated with education level, past pregnancy, current or past oral contraceptive use, or the age at first intercourse. In multivariate analysis, only the number of sexual partners during the last year and 1-5 years, and a previously abnormal Papanicolaou smear were associated with HPV. CONCLUSION: The presence of HPV DNA is best predicted by the number of new sexual partners in the last 5 years. Transiently detectable HPV DNA is one possible explanation for this observation.

Adolescent↗
PubMed1994

Simultaneous detection and typing strategy for human papillomaviruses based on PCR and restriction endonuclease mapping.

The aim of this study was to devise a simple and reliable method for simultaneous detection and typing of genital human papillomaviruses (HPVs). The method comprises three steps (i) amplification of sample DNA with the L1 consensus primers, (ii) digestion of PCR products with restriction endonuclease RsaI and (iii) hybridization of digested PCR products with a unique oligonucleotide probe that detects different fragments of the six most common genital HPV genotypes, namely, HPV types 6, 11, 16, 18, 31 and 33. Seventeen clinical specimens were analyzed by this method and compared to Southern blot using full genomic HPV DNA probes and to PCR using type-specific probes. All three tests agreed with at least one HPV type; however, the new method identified more additional HPV types in cases of mixed infections.

Base Sequence↗
PubMed1994

Cationic amino acid transport in human T lymphocytes is markedly increased in the CD45RA, CD8+ population after activation.

Membrane transport of cationic amino acids is essential for cells which are actively metabolizing L-arginine or L-lysine. In human cells most of this transport occurs through y+, a transport system which is only now being characterized at the molecular level. We have previously shown that phytohaemagglutinin (PHA) stimulation of peripheral blood E rosette positive (T) lymphocytes specifically activated lysine transport through system y+, whereas Staphlyococcus aureus Cowan A (SAC) stimulation of the E rosette negative fraction did not. We have now analysed this effect in PHA-activated CD4, CD8, CD45RO and CD45RA T-cell subsets. Both PHA-activated CD4+ and CD8+ T cells have increased lysine transport through y+, and in seven out of eight experiments, more activity was seen in the CD8+ fraction. In contrast, marked differences in y+ activity were seen between the PHA-activated CD45RO and CD45RA subsets. Thus in six experiments y+ activity was markedly increased in the CD45RA (naive T cell) population but not in the CD45RO (memory) cells. In one further experiment the activated CD45RO, CD4- population (enriched for CD45RA+, CD8+) was studied and y+ activity was shown to be maximal in this cell subset. Transport of arginine is essential for nitric oxide synthesis. Our findings therefore suggest that activated CD45RA, CD8+ T cells are capable of nitric oxide production.

Adult↗
PubMed1994

Topographic distribution and quantitative analysis of retrograde-labelled cells in the substantia nigra following administration of fluoro gold in the caudate putamen nucleus.

The organization of the efferent projections of the substantia nigra following the injection of 0.4 microliters of 2% Fluoro Gold into the caudate-putamen nucleus of rats of both sexes was studied. After a survival period of 72 h, the greatest number of labelled cells was visualized in the substantia nigra, with lower numbers in adjacent structures (ventral tegmental area, zona incerta and medial lemniscus). The cells featured an intensely fluorescent gold-coloured soma and were varied in shape (round or oval); short sinuous projections arose out of them, corresponding to the dendrites and axons of the neurons. In the statistical study, no significant differences were observed between males and females. A similar pattern of distribution was found ranging from the rostral to the caudal regions of the substantia nigra, occupying the whole of the extent of the substantia nigra; this distribution was most predominant in the rostro-caudal transition of the pars compacta of the substantia nigra.

Animals↗
PubMed1994

TaqStart Antibody: "hot start" PCR facilitated by a neutralizing monoclonal antibody directed against Taq DNA polymerase.

The specificity and DNA yield of PCRs are often improved by the "hot start" technique and analogous methods. The intent of the approach is to eliminate or prevent the generation of nonspecific PCR templates that may be synthesized at ambient temperature prior to thermal cycling. Monoclonal antibodies (MAbs) raised in mice to the purified DNA polymerase of Thermus aquaticus (Taq) were selected for their ability to reversibly block polymerase activity. The MAbs, incubated with Taq DNA polymerase and added to PCR tubes at ambient temperature, yield specific DNA fragments upon amplification when using high numbers of temperature cycles and a very low copy number of target DNA in a complex DNA background. This approach, using the TaqStart Antibody, permits the preparation of reaction mixtures at ambient temperatures without the subsequent opening of reaction tubes, use of grease or waxes, or of degradative enzymes and deoxyribonucleotide analogs.

Antibodies, Monoclonal↗