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Biomedical subjects

P Feng

Publications and source records attributed to P Feng.

At least 55 records · Page 3Linked to original sources
PubMed2000

An instrumental method for long-term continuous REM sleep deprivation of neonatal rats.

STUDY OBJECTIVES: The present study describes a new method for instrumental REM sleep deprivation (RSD) of neonatal rats. DESIGN: In the new method, an experimental neonatal rat and a yoked control neonatal rat were singly housed in a small plexiglass chamber which was divided into two separate units by a vertical wall. The floor of the housing chamber was attached to the platform of a standard laboratory test tube shaker. EEG and EMG electrodes were implanted by the soft head plug method which permitted continuous, long-term polysomnography. EEG and EMG signals were sent to a computer that was programmed to turn on the shaker for 5 seconds whenever the experimental rat entered REM sleep. SETTING: NA PATIENTS: NA INTERVENTIONS: NA RESULTS: The shaking of the chamber usually terminated REM sleep by entry to slow-wave sleep or wake. Amount of RSD depended on the shaker's oscillation speed. At higher speed the method reduced REM sleep by more than 80%. CONCLUSIONS: Thus, the new instrumental method of RSD can be used to study developmental functions of neonatal REM sleep. In particular, the instrumental method can test the hypothesis that in rats neonatal RSD produces the adult depressogenic effect of neonatally administered clomipramine.

Age Factors↗
PubMed2000

A new method for continuous, long-term polysomnographic recording of neonatal rats.

STUDY OBJECTIVES: Many findings suggest that in altricial mammals neonatal REM sleep has developmental functions. However, investigations of these developmental functions has been hampered by technical limitations of the conventional polysomnographic (PSG) recording technique. One limitation is that continuous (24 hour/day), long-term (weeks) PSG recordings have not been achieved. A second limitation is that the metal screw electrodes and head plugs cemented to the skull cannot be removed to allow the neonate to mature into adulthood. As a result of these limitations, the relationship between neonatal sleep/wake variables and adult variables has not been studied. Also the effects of polysomnographically controlled neonatal REM sleep deprivation on adult variables have not been studied. The present work describes a new technique called the soft head plug (SH) method for continuous, long-term PSG recording. DESIGN: In the new technique, electrodes are thin, strong, Teflon wires that are led by a suturing needle through the soft skull to the epidural space, then with a U-turn exited from the skull and tied to the entry wire. Thus, in contrast to the conventional technique, the soft head plug technique does not use screws as electrodes and does not cement a hard, relatively large electrode plug to the skull, removal of which is fatal or very traumatic. The SH recording electrodes can be removed without damage to neonates. SETTING: NA. PATIENTS: NA. INTERVENTIONS: NA. RESULTS: In the present study sleep/wake results with the soft head plug technique were reliable (replicated) and, compared with results of the conventional method, valid. CONCLUSIONS: The results indicate that the soft head plug technique can be used to study relationships between neonatal sleep/wake variables and adult variables.

Age Factors↗
PubMed2000

Multiplex PCR for detection of trait and virulence factors in enterohemorrhagic Escherichia coli serotypes.

A multiplex PCR assay was developed which allowed the simultaneous detection of five trait genes or virulence markers in enterohemorrhagic Escherichia coli (EHEC) serotypes. A primer pair, designed to detect a single base-pair mutation in the uidA gene, is specific only for the prototypic EHEC of O157:H7 serotype and its toxigenic, non-motile variants. In a similar way, primers to the eaeA gene of the gamma-intimin derivative specifically detects strains in the EHEC 1 clonal group, which consists mostly of O157:H7 and some O55:H7 serotypes. The other three primer pairs, specific for stx1, stx2 and both variants of ehxA genes, will detect the presence of these virulence genes in all EHEC serotypes. Analysis of 34 strains, including various serotypes of EHEC, Shiga toxin-producing E. coli and enteropathogenic E. coli, confirmed that the multiplex PCR assay detected the presence of these genes in a manner consistent with the known genotype of each respective strains.

Bacterial Proteins↗
PubMed2000

Rethinking technology, revitalizing ethics: overcoming barriers to ethical design.

This paper explores the role of ethics in design. Traditionally, ethical questions have been seen as marginal issues in the design of technology. Part of the reason for this stems from the widely held notion of technology being "out of control." This notion is a barrier to what I call "ethical design" because it implies that ethics has no role to play in the development of technology. This view, however, is challenged by recent work in the field of Science and Technology Studies (STS). Looking into the dynamics of technological change, STS scholars argue that human choices are present at every stage of a technology's development and, furthermore, that human values are reflected in the very design of artifacts. This alternative view suggests that ethics can and should be included in the design process. Drawing on examples from the privacy arena, I point to some of the potential advantages of addressing ethical concerns early on in the design of a technology. I conclude with some general strategies for bringing ethics back into design.

Ethics↗
PubMed2000

Ontogeny of REM sleep in rats: possible implications for endogenous depression.

Nine neonatal Long-Evans rats had continuous (24 h/day) polysomnography for 2 weeks, from age 14 days through age 27 days. A new finding was that six more or less independent measures of REM sleep occurrence decreased in parallel from age 14 days to age 27 days. The measures included parallel decreases of four measures of 24-h REM duration (tonic REM sleep, phasic REM sleep, mean REM period duration, and number of REM periods) along with parallel increases of two measures of REM delay (REM latency and percent of nonsleep onset REM periods). A parsimonious interpretation of the correlated changes is that a common developmental REM sleep inhibitory process accounts for the six parallel changes over time. This hypothesis can be tested empirically by studying inhibitory processes that operate on the pedunculopontine tegmental/latero-dorsal tegmental nuclei, the generators of REM sleep. The study also noted that compared with (same species) normal adults, endogenous depressives had the same distinctive REM sleep characteristics as neonatal rats. The similarity suggests that an underdeveloped, relatively weak REM sleep inhibitory process may account for the REM sleep peculiarities of endogenous depression. This hypothesis can be tested in adult rats made "depressed" by neonatal treatment with antidepressant drugs. Thus, the ontogeny of REM sleep suggests a developmental process that may be altered in humans predisposed to endogenous depression, and may account for the (life-long) REM sleep abnormalities of the disorder.

Aging↗
PubMed2000

Detection of Escherichia coli O157:H7 in heifers' faecal samples using an automated immunoconcentration system.

Pre-treatment of a 5-h enrichment culture with an automated immunoconcentration (ICE) system greatly improved the isolation of Escherichia coli O157:H7 from spiked heifer faecal samples. Enrichment samples plated directly onto sorbitol MacConkey agar (SMAC) and SMAC agar supplemented with cefixime and potassium tellurite (CT-SMAC) showed recovery rates of 8% and 56%, respectively. However, after ICE treatment, E. coli O157:H7 was recovered from 92% of the samples on SMAC and 100% on CT-SMAC. Immunoconcentration analysis of heifers' faecal samples collected from a slaughter-house in France, during March to June 1998, showed that 1% (three of 300) was positive for E. coli O157:H7. Phenotypic and genotypic analysis showed that all three isolates carried both the O157 and H7 antigens, did not ferment sorbitol or had beta-glucuronidase activity and carried trait virulence factors for E. coli O157:H7 (uidA allele, eaeA and pO157 plasmid). However, only one strain was toxigenic and this strain produced a single toxin, namely verotoxin 2.

Adhesins, Bacterial↗
PubMed2000

Effect of high-oil corn on growth performance, diet digestibility, and energy content of finishing diets fed to beef cattle.

Sixty crossbred beef steers (initial BW = 412 kg) were used in a 83-d finishing study to determine the effect of feeding dry rolled high-oil corn on performance and total-tract digestibility of finishing diets. Steers were allotted by weight to the following dietary treatments: 1) control corn (C; 82% normal corn, 12% triticale silage), 2) high-oil corn (HO; 82% high-oil corn, 12% silage), and 3) high-oil corn formulated to be isocaloric to C (ISO; 74% high-oil corn, 20% silage). Total lipid content was 4.9% (DM basis) for normal corn and 7.0% for high-oil corn. Steers were individually fed using electronic gates. Quantity of feed offered and refused was recorded daily. Fecal samples were collected on d 63 to 66 of the trial to determine digestibility. Chromic oxide was fed as an indigestible marker for 7 d before fecal collection began. Planned contrasts of HO vs C and ISO vs C were used to assess treatment differences. Dry matter intake was greater for steers fed C vs HO (P < 0.01) or C vs ISO (P < 0.01), but daily gain and feed efficiency were not affected (P > 0.05) by treatments. Digestibility of DM, OM, starch, and GE was greater (P < 0.05) for the HO diet than the C diet, but lipid digestibility did not differ among treatments (P > 0.05). The combined effect of greater GE content and digestibility resulted in greater (P < 0.01) DE content for the HO than for the C diet. Calculated DE of the corn was 8.3% greater (3.74 Mcal/kg; P < 0.01) for the HO diet and 6.5% greater (3.67 Mcal/kg; P < 0.01) for the ISO diet than the corn in the C diet (3.25 Mcal/kg). Dry matter and GE digestibility did not differ (P > 0.05) between the C and ISO diets. Steers consuming ISO had greater (P < 0.05) starch digestibility than steers fed the C diet. Although HO had higher DE, DE intake was similar (P > 0.05) for HO and C due to lower DMI for HO. These results indicate that available energy is greater from high-oil corn than from typical corn, but depressed voluntary feed intake prevented performance improvements and resulted in equal energy intakes between high-oil corn and typical corn diets.

Animal Feed↗
PubMed2000

Zinc induces mitochondria apoptogenesis in prostate cells.

BACKGROUND AND PURPOSE: Prostate secretory epithelial cells have the unique function and capability of accumulating extremely high intracellular levels of zinc. One of the effects of this accumulation is inhibition of cell growth due, in part, to an increase in apoptosis. The present studies were conducted to determine if this zinc-induced apoptosis involves stimulation of mitochondrial apoptogenesis. MATERIALS AND METHODS: The PC-3 a human malignant prostate cell line, which is zinc accumulating, was exposed to medium supplemented with physiologic levels of zinc. RESULTS: By 24 h, zinc treatment resulted in the translocation of cytochrome c from the mitochondria to the cytosol, the activation of caspase-9 and caspase-3, and eventually, the cleavage of nuclear poly(ADP)-ribose polymerase (PARP). Under similar conditions, exposure of freshly prepared rat ventral prostate cells (which are also zinc accumulating) resulted in increased apoptosis following translocation of cyochrome c and activation of caspases-9 and 3. The human prostate PZ-HPV-7 cells, which do not accumulate zinc, did not exhibit any apoptotic effect from zinc treatment. CONCLUSION: The accumulation of high intracellular levels of zinc by prostate cells induces mitochondrial apoptogenesis. This represents a newly identified physiological effect of zinc in the regulation of prostate cell growth.

Animals↗
PubMed2000

Antioxidant activity of qizhu tang.

AIM: To study the antioxidant, activity of Qizhu Tang (QZT) both in vivo and in vitro. METHODS: QZT consists of 4 herbal constituents (Rhizoma Atractylodis Macrocephalae, Poria cocos, Kadix Notoginseng, and Radix Astragali), each of the components and their combinations were examined in vitro for 1, 1-diphenyl-2-picrylhydrazyl (DPPH) and hydroxyl radical scavenging activities, and for the inhibition of thiobarbituric acid-reactive substances (TBARS) formation in rat liver homogenate. At the same time, their in vivo protective effect on cerebral ischemia-areperfusion injury was determined in rats. RESULTS: Only the preparations having a higher antioxidant activity comparable to QZT in all three in vitro assays were relatively active in vivo both for TBARS inhibition and glutathione peroxidase preservation, although the activities were much lower than that of QZT as a whole. CONCLUSION: QZT formula is a good natural antioxidant having an effective preventive effect against cerebral ischemia reperfusion damage.

Animals↗
PubMed2000

[Relations of glycemic control to diabetic nephropathy in patients with non-insulin-dependent diabetes mellitus (NIDDM)--a pair-matched case-control study].

OBJECTIVE: To describe the relations between glycemic control and development of diabetic nephropathy (DN) in patients with non-insulin-dependent diabetes mellitus (NIDDM). METHODS: A retrospective analysis was carried out on two groups of NIDDM patients, one group without proteinuria (< 300 mg/day, n = 106) and the other group with proteinuria (> or = 500 mg/day, n = 106). The two groups were matched by age <or= +/- 3yrs, sex, race and resident place. Information of these subjects including demographic, history of diseases, family history of diseases, life-style and behavior style was obtained by self-administered questionnaire. Variables including systolic blood pressure (SBP), diastolic blood pressure (DBP), fasting blood glucose (FBG), quantity of protein in 24-h urine were measured. Successful glycemic control denoted that the mean value of FBG's surveillance was less than 140 mg/dl after the occurrence of DM (the duration to the development of DN for the patients with DN.). Conditional logistic regression analysis was carried out. RESULTS: Results from univariate analysis showed that development of proteinuria was associated with glycemic control, the FBG level at diagnosis of NIDDM and the highest FBG level in the past. The corresponding odd ratios (OR) with 95% confidence intervals (CI) were 0.43 (0.25 - 0.75); 1.34 (1.05 - 1.72) and 1.35 (1.07 - 1.70) respectively. When data were adjusted by possible confounding factors, the relation of glycemic control to DN still existed, but the other two relations disappeared. CONCLUSION: Successful glycemic control decreased the occurrence risk of DN, independent of other risk factors including diabetic duration.

Adult↗
PubMed2000

[Study on uptake of fluoroquinolones by Staphylococcus aureus].

This study aimed to investigate the mechanism of Staphylococcus aureus' resistance to fluoroquinolones. The uptake of lomefloxacin, ofloxacin by Staphylococcus aureus and the effect of CCCP on the uptake were studied by the fluorescence method. The uptake of lomefloxacin, ofloxacin by sensitive organisms is higher than that by resistant organisms; CCCP had different influences on different organisms, but no significant difference between the effects of CCCP on sensitive strains and on resistant strains was noted. The uptake of lomefloxacin, ofloxacin by SA2-16 was much lower than that by SA2-16's parent, and after the addition of CCCP, the uptake of both quinolones by SA2-16 increased rapidly, but the concentration did not reach its parent's concentration in stable condition. These results indicate that the decreasing of the uptake of fluoroquinolones is one of the mechanisms responsible for Staphylococcus aureus to resistance fluoroquinolones, and as a mechanism of resistance to drugs, it plays different roles in different strains.

Anti-Infective Agents↗
PubMed2000

[Protective effect of total paeony glycoside against cerebral ischemia-reperfusion injury in mice].

OBJECTIVE: To investigate actions of Total Paeony Glycoside (TPG) on cerebral ischemia-reperfusion model in mice. METHODS: The cerebral ischemia-reperfusion models induced by lagation of bilateral common carotid arteries incompletely were used. RESULTS: It was found that TPG could improve the learning and memory capacity of model mice in step down test. TPG significantly reduced the decrease of superoxide dismutase(SOD), inhibited the increase of nitric oxide(NO) and lessened the level of malondialdehyde(MDA) in model mice. 75 mg.kg-1 TPG also reduced the decrease of lactate dehydrogenase (LDH) in cerebrum remarkedly. CONCLUSION: It is suggested that TPG possess obvious protective effects against cerebral ischemia-reperfusion mice.

Animals↗
PubMed2000

Role of endogenous carbon monoxide in endotoxin shock.

OBJECTIVE: To study the role of endogenous carbon monoxide (CO) in endotoxin shock. METHODS: The changes of CO levels and the effects of zinc protoporphyrin IX (ZnPP), an inhibitor of heme-oxygenase (HO), in endotoxin shock and the efficacy of hemin, an inducer of HO were investigated. RESULTS: The plasma CO levels were found to be significantly increased during the course of endotoxin shock. Injection of ZnPP was shown to abrogate the endotoxin-induced hypotension and metabolic derangements markedly. Administration of hemin to healthy rabbits revealed the hypotension and metabolic derangements similar to the animals given endotoxin. CONCLUSION: CO is a newly found endogenously produced mediator which may play an important role in the pathogenesis of endotoxin shock.

Animals↗
PubMed1999

Inhibitory effect of zinc on human prostatic carcinoma cell growth.

BACKGROUND: Normal human prostate accumulates the highest levels of zinc of any soft tissue in the body. In contrast, the zinc level in prostate cancer is markedly decreased from the level detected in nonprostate tissues. Despite these relationships, the possible role of zinc in the growth of normal and malignant prostate has not been determined. METHODS: Growth inhibition and various regulatory responses were investigated in two human prostate carcinoma cell lines (LNCaP and PC-3), treated with or without zinc. RESULTS: Incubation of the prostate carcinoma cell lines with physiological levels of zinc resulted in the marked inhibition of cell growth. A lower 50% inhibition of cell growth (IC50) value for zinc (about 100 ng/ml) was detected in LNCaP cells, which are androgen-responsive, whereas androgen-independent PC-3 cells exhibited a higher IC50 for zinc (about 700 ng/ml). Incubation with 1 microg/ml zinc resulted in maximum inhibition of growth in both cell lines. These inhibitory effects of zinc correlated well with the accumulation of zinc in the cells. Simultaneously, cell flow cytometric analyses revealed a dramatic increase of the cell population in G2/M phase, in both LNCaP (2.3-fold vs. control) and PC-3 (1.9-fold vs. control), and a decreased proportion of cells in S phase (LNCaP, -51.4%; PC-3, -23%), indicating a G2/M phase arrest. The cell growth inhibition and G2/M arrest in these cells were accompanied by an increase in apoptosis, as demonstrated by the characteristic cell morphology and further confirmed by cellular DNA fragmentation. The specificity of zinc-induced apoptosis was identified by ethylenediamine-tetraacetic acid (EDTA)-chelation, which abolished the zinc effect on cellular DNA fragmentation. The zinc-induced G2/M phase arrest and apoptosis were accompanied by increased mRNA levels of p21(Waf1/Cip1/Sdi1) in both LNCaP (p53+/+) and PC-3 (p53-/-) cells. CONCLUSIONS: These results suggest that zinc inhibits human prostatic carcinoma cell growth, possibly due to induction of cell cycle arrest and apoptosis. There now exists strong evidence that the loss of a unique capability to retain high levels of zinc is an important factor in the development and progression of malignant prostate cells.

Apoptosis↗
PubMed1999

BLyS: member of the tumor necrosis factor family and B lymphocyte stimulator.

The tumor necrosis factor (TNF) superfamily of cytokines includes both soluble and membrane-bound proteins that regulate immune responses. A member of the human TNF family, BLyS (B lymphocyte stimulator), was identified that induced B cell proliferation and immunoglobulin secretion. BLyS expression on human monocytes could be up-regulated by interferon-gamma. Soluble BLyS functioned as a potent B cell growth factor in costimulation assays. Administration of soluble recombinant BLyS to mice disrupted splenic B and T cell zones and resulted in elevated serum immunoglobulin concentrations. The B cell tropism of BLyS is consistent with its receptor expression on B-lineage cells. The biological profile of BLyS suggests it is involved in monocyte-driven B cell activation.

Amino Acid Sequence↗
PubMed1999

Synthetic retinoid CD437 induces S-phase arrest and apoptosis in human prostate cancer cells LNCaP and PC-3.

BACKGROUND: Exposure of prostate carcinoma cell lines to retinoids, which function through the classical retinoic acid nuclear receptor, (RARs) or retinoid X receptors (RXRs), results in minimal cytostatic inhibition of cell proliferation. METHODS: Growth inhibition and various regulatory responses were investigated in two human prostate carcinoma cell lines (LNCaP and PC-3) treated with or without a synthetic retinoid, CD 437. RESULTS: Incubation of prostate carcinoma cell lines with a novel retinoid CD437 resulted in the marked inhibition of proliferation. LNCaP and PC-3 possessed IC50 values for CD437 of 375 nM and 550 nM, respectively. Incubation with 1 microM CD437 for 24 hr resulted in 100% and 60% inhibition of growth in LNCaP and PC-3 cells, respectively. Simultaneously, cell flow cytometric analyses revealed a dramatic increase of the cell population in S phase, in both LNCaP (from 38.6% up to 86.7%) and PC-3 (27.9% to 55.7%), and a decreased proportion of cells in G2 phase, in LNCaP (from 23.7% down to 1.2%) and PC-3 (14.9% to 2.2%), indicating a significant S-phase arrest. The cell growth inhibition and S-phase arrest in these cells were followed by apoptosis, as revealed by the acquisition of the characteristic cell morphology including the appearance of apoptotic bodies, and further confirmed by cellular DNA fragmentation. CD437-induced-S phase arrest was associated with upregulated mRNA levels of p21waf1/cip1/sdi1 in both LNCaP (p53+/+) and PC-3 (53-/-) cells. CONCLUSIONS: CD437 represents a unique retinoid that induces S-phase arrest and apoptosis in both androgen-dependent (LNCaP) and -independent (PC-3) human prostate cancer cells, suggesting a potential role of CD437 in the treatment of human prostate cancer.

Antineoplastic Agents↗
PubMed1999

DNA probe analysis for the carriage of enterotoxigenic Clostridium perfringens in feces of a Mexican subpopulation.

Clostridium perfringens has been implicated as a causative agent of foodborne poisoning, infectious diarrhea (not associated with foods), gas gangrene, and several veterinary diseases. Fecal carriage of enterotoxigenic strains of this bacterium appears to be important in the development of infectious diarrhea and as a source of C. perfringens contamination of foods. In this work, carriage of this bacterium in feces of a Mexican population was analyzed. C. perfringens was found in 126 of the 200 fecal samples obtained from healthy individuals from northern Mexico. The samples had an average of 7.4 x 10(3) spores per gram, with the elderly population showing the highest levels. Dot blot analyses using a dig-labeled probe specific for the enterotoxin gene showed that 7% of the samples had isolates with toxigenic potential.

Adolescent↗