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Biomedical subjects

P Ren

Publications and source records attributed to P Ren.

At least 19 recordsLinked to original sources
PubMed2001

Catalytic asymmetric allylic C-H activation as a surrogate of the asymmetric Claisen rearrangement.

[reaction: see text]. Tetrakis[N-[4-dodecylphenyl)sulfonyl]-(S)-prolinato]-dirhodium [Rh2(S-DOSP)4] catalyzed decomposition of methyl aryldiazoacetates in the presence of alkenes results in allylic C-H activation by means of a rhodium-carbene induced C-H insertion. The resulting gamma,delta-unsaturated esters are equivalent to products that would be traditionally obtained from an asymmetric Claisen rearrangement. Highly regio- and enantioselective C-H insertions can be achieved, and in certain cases, good diastereocontrol is also possible.

Journal Article↗
PubMed2001

Synthesis of 2beta-acyl-3beta-(substituted naphthyl)-8-azabicyclo[3.2.1]octanes and their binding affinities at dopamine and serotonin transport sites.

A series of 3beta-naphthyltropane derivatives were synthesized and found to show high affinity at both the dopamine and serotonin transporter sites, leading to some of the most potent inhibitors known based on the tropane structure. Comparative molecular field analysis (CoMFA) models were developed for both dopamine and serotonin transporter binding data. These models provide insights into those factors that influence binding at the two transporters.

Animals↗
PubMed2001

The relation between fungal propagules in indoor air and home characteristics.

BACKGROUND: Questionnaires are commonly used in epidemiologic studies to obtain information about house characteristics in order to predict the household aeroallergen exposure levels. However, the reliability of the predictions made with the questionnaires has not been evaluated. To address this issue, we compared objectively measured fungal propagules including the most frequently isolated mold genera (i.e., Alternaria, Aspergillus, Cladosporium, Penicillium, etc.) in a large sample of homes and compared these measured values to the questionnaire-determined household characteristics. METHODS: As part of a prospective cohort study on the relation between residential allergen exposure and development of asthma in neonates, fungal air samples were collected from infant bedrooms and main living areas in 1000 homes in the Northeast USA, from December 1996 to January 1999. A Burkard portable air sampler was used in combination with DG-18 and MEA agars. A questionnaire was used to obtain information on host and house characteristics that may have an impact on the presence of fungal propagules in the air. This included information on observation of moisture problems (e.g., water leakage or damage, and mold or mildew growth), ventilation and heating facilities, building age and type, number of occupants, annual household income, presence of pets and pests, cleaning regimens, etc. RESULTS: The number of CFU/m3 air collected on MEA was significantly higher than on DG-18 (means, respectively, 1033.5 and 846.0 CFU/m3) (P < 0.0005). However, there was no significant difference between the numbers of CFU/m3 air collected from the main living area and from the infant bedroom. There was only a very weak relationship between the house characteristics, as described by questionnaire, and the presence of fungal propagules in indoor air. Only the temperature, relative humidity, season, and cats inside homes had a statistically significant impact on the presence of fungal propagules in indoor air. CONCLUSION: The presence of fungal propagules in indoor air cannot be reliably predicted by home characteristics. Actual measurements are required for fungal exposure assessment, and the use of only one medium to collect samples in one location in a home might be adequate to represent residential levels of fungi in indoor air.

Air Microbiology↗
PubMed2001

High-throughput detection of West Nile virus RNA.

The recent outbreaks of West Nile virus (WNV) in the northeastern United States and other regions of the world have made it essential to develop an efficient protocol for surveillance of WNV. In the present report, we describe a high-throughput procedure that combines automated RNA extraction, amplification, and detection of WNV RNA. The procedure analyzed 96 samples in approximately 4.5 h. A robotic system, the ABI Prism 6700 Automated Nucleic Acid workstation, extracted RNA and set up reactions for real-time reverse transcription (RT)-PCR in a 96-well format. The robot extracted RNA with a recovery as efficient as that of a commercial RNA extraction kit. A real-time RT-PCR assay was used to detect and quantitate WNV RNA. Using in vitro transcribed RNA, we estimated the detection limit of the real-time RT-PCR to be approximately 40 copies of RNA. A standard RT-PCR assay was optimized to a sensitivity similar to that of the real-time RT-PCR. The standard assay can be reliably used to test a small number of samples or to confirm previous test results. Using internal primers in a nested RT-PCR, we increased the sensitivity by approximately 10-fold compared to that of the standard RT-PCR. The results of the study demonstrated for the first time that the use of an automated system for the purpose of large-scale viral RNA surveillance dramatically increased the speed and efficiency of sample throughput for diagnosis.

Animals↗
PubMed2001

[Determination of ferulic acid absorbed into human serum from oral decoction of rhizoma chuanxiong and pharmacokinetic study of ferulic acid].

OBJECTIVE: To improve the HPLC method for determining ferulic acid(FA) in the human serum and to research FA clinical pharmacokinetics. METHOD: Serum concentrations of FA were determined by HPLC using methanol-water-acetic acid (40:59.7:0.3, v/v) as the mobile phase and the column packed with ODS (150 mm x 4.6 mm, 5 microns) as a fixed phase and the flow rate was 1.0 ml/min. FA was detected at 320 nm wave length. The internal standard was coumarin. The serum samples were treated by the water-boiling method. Peak of FA in serum was recognized by photodiode-array detection. RESULT: FA and internal standard were separated completely under the condition described as above. FA was linear in the range of (40.16-8032 ng/ml) (r = 0.9975). The CV was less than 10%, the average recovery was 100.3%, and the limit concentration in serum was 25.1 ng/ml. PK was in accordance with open bicameral model. CONCLUSION: This method can be applied to clinical pharmacokinetic study of FA.

Adult↗
PubMed2001

[Effect of combination of Chinese herbal drugs on clinical bioavailability of ferulic acid in serum].

OBJECTIVE: To observe the effect of combination of Chinese herbal drugs on bioavailability of Ligusticum walichii (LW) derived ferulic acid (FA) in serum. METHODS: Healthy volunteers were given LW decoction (1 g/kg), LW combined with Paeonia veitchii (PV, 1:1) decoction (2 g/kg) and Coronary Heart No. 2 (CH-II, 3 g/kg, containing LW 0.5 g/kg) once respectively. The serum FA concentration-time (c-t) curve was performed by HPLC using the method established by the authors, and the area under that curve (AUC) was calculated and compared. RESULTS: The FA c-t curve in the three groups was double peak curve. As compared with the AUC in subjects who were administered LW decoction, the AUC in those taken LW + PV decoction was lower [(15734.88 +/- 7737.97) ng/(min.ml) vs (5717.92 +/- 6124.63) ng/(min.ml)], P < 0.05), while that in those taken CH-II was relatively higher [(8072.00 +/- 4424.31) ng/(min.ml), P > 0.05)]. CONCLUSION: Combination of LW and PV could significantly lower the bioavailability of FA, but when LW was added in CH-II, the FA bioavailability was not affected.

Adolescent↗
PubMed2000

An exploratory study of type II [3 + 4] cycloadditions between vinylcarbenoids and dienes.

The intramolecular type II [3 + 4] cycloaddition between vinylcarbenoids and furans is a practical method for the construction of 5-oxo-10-oxatricyclo[6.2.1.0(4,9)]undeca-3, 8(11)-dienes, containing two anti-Bredt double bonds. These tricyclic systems are well functionalized for eventual elaboration to the natural product CP-263,114. The rhodium-stabilized vinylcarbenoids are generated by dirhodium tetracarboxylate catalyzed decomposition of vinyldiazoacetates. The [3 + 4] cycloaddition is generally considered to occur by a tandem cyclopropanation/Cope rearrangement, although evidence is presented that with these substrates the [3 + 4] cycloaddition may occur in a concerted manner.

Alkenes↗
PubMed2000

Expression of an intestine-specific transcription factor (CDX1) in intestinal metaplasia and in subsequently developed intestinal type of cholangiocarcinoma in rat liver.

CDX1 is a caudal-type homeobox intestine-specific transcription factor that has been shown to be selectively expressed in epithelial cells in intestinal metaplasia of the human stomach and esophagus and variably expressed in human gastric and esophageal adenocarcinomas (Silberg DG, Furth EE, Taylor JK, Schuck T, Chiou T, Traber PG: Gastroenterology 1997, 113: 478-486). Through the use of immunohistochemistry and Western blotting, we investigated whether CDX1 is also uniquely associated with the intestinal metaplasia associated with putative precancerous cholangiofibrosis induced in rat liver during furan cholangiocarcinogenesis, as well as expressed in neoplastic glands in a subsequently developed intestinal type of cholangiocarcinoma. In normal, control adult rat small intestine, specific nuclear immunoreactivity for CDX1 was most prominent in enterocytes lining the crypts. In comparison, epithelium from intestinal metaplastic glands within furan-induced hepatic cholangiofibrosis and neoplastic epithelium from later developed primary intestinal-type cholangiocarcinoma each demonstrated strong nuclear immunoreactivity for CDX1. CDX1-positive cells were detected in hepatic cholangiofibrotic tissue as early as 3 weeks after the start of chronic furan treatment. We further determined that the percentages of CDX1-positive neoplastic glands and glandular nuclei are significantly higher in primary tumors than in a derived, transplantable cholangiocarcinoma serially-propagated in vivo. Western blotting confirmed our immunohistochemical results, and no CDX1 immunoreactivity was detected in normal adult rat liver or in hyperplastic biliary epithelial cells. These findings indicate that CDX1 is specifically associated with early intestinal metaplasia and a later developed intestinal-type of cholangiocarcinoma induced in the liver of furan-treated rats.

Animals↗
PubMed2000

[Observation on efficacy of puerarin in treating diabetic retinopathy].

OBJECTIVE: Using promoting blood circulation to remove stasis principle to observe arteria and vena centralis retinae blood flow indexes, and hemorrheology of diabetic retinopathy patients with Puerarin. METHODS: Thirty patients with diabetic retinopathy were randomly divided into the treated group (n = 15) and the control group (n = 15). The treated group were given Puerarin 400 mg per day intravenously dripping. The control group were given Mikebao 500 micrograms intramuscularly, once per day. Both groups were taken 3 consecutive weeks as one treatment course. Two courses later, observing hemorrheologic parameters, arteria and vena centralis retinae blood flow indexes. RESULTS: Comparing before and after treatment the RBC aggregation index, the whole blood viscosity rate, plasma viscosity rate, fibrinogen and erythrocyte sedimentation rate, have improved obviously (P < 0.05, P < 0.01). Comparing with the control group, there was significant difference (P < 0.05, P < 0.01). The difference of treated group between before and after treatment, the peak systolic velocity (PSV) of arteria centralis retinae, their end diastolic volume (EDV), the acceleration (A), the central retinal vein reflux velocity (CRV) have improved respectively. Naked eye visions were also improved, comparing with the control group, the difference was significant (P < 0.01). CONCLUSION: Puerarin can reduce blood viscosity, improve microcirculation, and plays a positive therapeutic role in diabetic retinopathy.

Adult↗
PubMed2000

[Effect of sijunzi decoction on gastric emptying rate in rat model of spleen deficiency syndrome].

OBJECTIVE: To observe the effect of Sijunzi decoction (SJZ) on gastric emptying rate in rat model of Spleen Deficiency Syndrome (SDS) and to explore the mechanism of "Yiqi Jianpi" (replenishing Qi and invigorating Spleen) effect with gastroduodenal myoelectrical activity and brain-gut peptide concentration. METHODS: After intramuscular injection of reserpine for 14 days, the rat model of SDS was established. Rats were randomly divided into 5 groups, group A treated by SJZ, group B treated by Liuwei Dihuang decoction (LWDH), group C naturally recovered, group D SDS rat model, consecutively treated for 14 days, and compared with group E, the normal control. Using radioisotopic technique to monitor 30 min gastric liquid emptying rate, and using the implanted bipolar silver electrode to observe the antral and duodenal myoelectrical slow wave, and the plasma and hypothalamus levels of motilium (MOT), cholecystokinin (CCK) and somatostatin (SS) were measured by radioimmunoassay (RIA) 14 days later respectively. RESULTS: Compared with the normal control, gastric liquid emptying rate of rat SDS model was lowered (P < 0.01, P < 0.05); the hypothalamus and plasma levels of MOT and SS reduced, both hypothalamus and plasma had higher CCK levels (P < 0.01, P < 0.05); in comparing with the controls, the rhythm, amplitude and motility index of myogastric slow wave were lower also. After treated with SJZ, the aforesaid data were normalized with insignificant difference in comparing with the normal control (P < 0.01), but the rat SDS model treated by LWDH and in natural recovery had no significant improvement. CONCLUSION: SJZ can promote gastric liquid emptying rate of rat SDS model by improving the myogastric electrical movement as well as regulating the levels of MOT, CCK and SS.

Animals↗
PubMed1999

[Direct determination of serum content of ferulic acid treated with boiling water in HPLC in volunteers after oral Administration of Coronary Heart No. II decoction].

OBJECTIVE: To develop a new method for clinical pharmacokinetic detection of chemical component of Coronary Heart NO. II in serum after oral administration in healthy person. METHODS: Content of ferulic acid (FA) in serum, which had been treated with boiling water bath, was determined directly by high performance liquid chromotography (HPLC) and spectrophotometer. After qualitative detection performed by using Bi- and tri-dimensional HPLC and ultraviolet spectrophotometer, the quantitative detection was determined with the internal standard (coumarin). RESULTS: When eluted by mobile phase of a mixture of methanol, acetic acid and water (38:0.3:61.7 in ratio), and stationary phase of C18(ODS2), column (150 mm x 4.6 mm, 5 microns), the minimal detectable limit of free methanol FA was 6 ng (N/S = 3), and the minimal detectable serum FA concentration, after 10 min of boiling water bath, was 20.2 micrograms/L, with a linearity of 33.7-2156.8 micrograms/L, r = 0.9993. The mean recovery of serum FA was (93.59 +/- 2.36) micrograms/L. The RSD within day and day-to-day were all less than 8.44%. CONCLUSION: In comparing with sample Preparation of acetonitrile, this method is simple, rapid, sensitive, cheap, accurate, specific, reproducible and no toxic.

Adolescent↗
PubMed1999

[Transplantation of neural retina after photic injury of retina in mice].

OBJECTIVE: To examine the possibility of retinal photoreceptors rescued after photic injury by allogeneic neural retinal transplantation. METHODS: The retinal photic injury model was established by a light-damage trunk designed by ourselves. After photo-illumination, 60 mice were divided into two groups: Group I (n = 20) was the photic injury group and group II (n = 40), the retinal transplantation group; then group II was subdivided into II(A) (n = 20) and II(B) (n = 20) subgroups. External approach for neural retinal transplantation was performed at 24hr (group II(A)) and day 7 (group II(B)) after photic injury respectively. The recipients were sacrificed at day 6, day 12, day 18 and day 30 post-operatively to examine whether the graft could rescue the injured retinal photoreceptors. RESULTS: In group I, the inner and outer segment showed edema, disorganization and vesiculation, the outer nuclear layer became very thin and disorganized, and the cell nuclear chromatin showed pyknosis and margination. In group II, the graft survival rate in group II(A) was 50% (10/20) and in group II(B) was 80% (16/20), the difference being significant (chi(2) = 3.956, P < 0.05). Among the graft survival samples, we compared the rescue rate of photoreceptors between group II(A) 40% (4/10) and group II(B) 50% (8/16), the difference being not significant (P = 0.702). CONCLUSION: The retinal photic injury may result in photoreceptor degeneration that can be rescued by retinal transplantation, and the successful rate of the transplantation performed at day 7 is higher than that at 24-hr after injury.

Animals↗
PubMed1999

[Mechanism of arsenic hydride generation and atomization in low temperature atomic fluorescence spectrometry].

With a hollow cathode lamp as exciting source, the optimum working parameters for the determination of As were selected. By adopting two hydride-generators to generate hydride and H2 simultaneously, the mechanism of AsH3 generation was studied. Experimental results show that the atomization process of AsH3 might be carried out mainly by collision with hydrogen radical.

English Abstract↗
PubMed1998

Mycotoxins of Alternaria alternata produced on ceiling tiles.

The production of mycotoxins by Alternaria alternata in cellulosic ceiling tiles was examined with thin-layer chromatography and high-performance liquid chromatography procedures. Alternariol and alternariol monomethyl ether were found in ceiling tile extracts, whereas extracts of control rice cultures of all three isolates produced these mycotoxins plus altenuene and altertoxin I. Extensive fungal growth and mycotoxin production occurred in the ceiling tiles at relative humidities of 84-89% and 97%.

Air Microbiology↗
PubMed1998

Inhibition of gap junctional intercellular communication by tumor promoters in connexin43 and connexin32-expressing liver cells: cell specificity and role of protein kinase C.

In this study, we investigated whether the tumor promoters, 12-O-tetradecanoylphorbol-13-acetate (TPA), phenobarbital (PB), and 1,1-bis(p-chlorophenyl)-2,2,2-trichloroethane (DDT), inhibited gap junctional intercellular communication (GJIC) in a cell-specific or connexin-specific manner and whether protein kinase C was involved. To do this, we used highly communicating WB-F344 rat liver epithelial cells, which express connexin43 as their predominant gap junction protein, WB-aB1 cells, which are a GJIC-incompetent mutant line of WB-F344 cells and that express connexin43, WB-a/32-10 cells, which are a highly communicating derivative of WB-aB1 cells generated by stable transduction with a connexin32 retroviral expression vector, and primary cultured rat hepatocytes, which express conexin32 predominantly. Treatment of WB-F344 and WB-a/32-10 cells, but not hepatocytes, with TPA inhibited GJIC (assayed by Lucifer Yellow dye microinjection). This inhibition involved protein kinase C because (i) inhibition was prevented by co-treatment of the cells with a specific protein kinase C inhibitor, bis-indolylmaleimide, and (ii) treatment with TPA for 24 h had no effect on dye-coupling in agreement with the downregulation of protein kinase C. TPA also caused the internalization of Cx43-containing gap junctions and the formation of a hyperphosphorylated form of Cx43, Cx43-P3, in WB-F344 cells only, but TPA had no effect on Cx32-containing gap junctions or protein mobility. In contrast, PB inhibited GJIC only in hepatocytes and DDT inhibited GJIC in all three types of cells; bis-indolylmaleimide did not block the effects of either agent. These results indicate that the inhibitory actions of TPA and PB on GJIC are cell-specific rather than connexin-specific and that TPA inhibits connexin43 and connexin32-mediated GJIC through a protein kinase C-dependent mechanism.

Animals↗
PubMed1998

[HBV markers in severe hepatitis B].

In order to elucidate the relationship between hepatitis B virus (HBV) replication and severity of hepatitis B, HBV serological markers and HBV-DNA in 56 patients with chronic hepatitis B were detected using the methods of ELISA and PCR, respectively. The results showed that the positive prevalence of HBeAg and/or HBV-DNA in chronic severe hepatitis B (5/25) was much lower than that in non-severe chronic hepatitis B (26/31) (P < 0.01). The study provides the suggestive evidence that viral replication is significantly reduced in severe hepatitis B. Also, increased replication of HBV appears to be not the cause of hepatic necrosis in severe hepatitis B.

Adult↗