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Biomedical subjects

J Luo

Publications and source records attributed to J Luo.

394 records · Page 22Linked to original sources
PubMed1988

Cloning of cDNA coding for carbamyl phosphate synthetase I and changes in levels of CPS1 mRNA during hepatocarcinogenesis.

cDNA coding for carbamyl phosphate synthetase I was cloned from recombinant plasmid with insert complementary to the mRNA for CPS1 followed by hybrid-selected translation screening. The length of the insert CPS1 cDNA was approximately 800 base pairs. Using this cDNA as a probe, it was found by dot-blot analysis of the total RNAs and poly(A)+-RNAs isolated from rat livers with different pathological lesions induced by diethylnitrosamine that the levels of CPS1 mRNA were decreased, the decrease being correlated with the malignancy of hepatocytes during carcinogenesis.

Animals↗
PubMed1983

An outline of population geography of Jiangsu province, China.

"Jiangsu (Kiangsu) Province [China] is located in the lower reaches of the Yangtze River which divides it into two parts, South Jiangsu and North Jiangsu. The area of the province is 102,000 sq. km with a population of 60,521,114 and a density of 605 per sq. km in 1982. The area of Jiangsu is slightly larger than that of Hungary (93,000 sq. km). But the population is 5.7 times and the density of population 5.2 times larger than those of Hungary. This paper states the tendency of population growth, the geographical distribution and present condition of urban and rural population, discussing briefly the rational redistribution of [the] population of Jiangsu."

Asia↗
PubMedDate not supplied

Study of phenformin metabolism in rat liver microsomes by HPLC, CE and on-line HPLC-electrospray ionization mass spectrometry.

Methods for the analysis of phenformin and its metabolite by high-performance liquid chromatography (HPLC), capillary electrophoresis (CE) and high-performance liquid chromatography-electrospray ionization mass spectrometry (HPLC-ESIMS) are developed. The effects of pH, buffer concentration and proportion of organic modifier on the retention of the compounds in HPLC have been studied. The optimum condition was used for the separation and identification of phenformin and its metabolite in microsomal metabolism by HPLC-ESIMS. A simple CE method is also described for the separation of these compounds. Optimum incubation conditions and cofactor requirements for the formation of 4-hydroxyphenformin by microsomal preparations of rat liver were determined. A linear response in the formation of product was found with increasing concentrations of protein and up to 15 min incubation. High concentrations of phenformin inhibited its metabolite formation, and K(m) was 4 microM.

Acetates↗
PubMedDate not supplied

Enantiomeric separation and detection by high-performance liquid chromatography-mass spectrometry of 2-arylpropionic acids derivatized with benzofurazan fluorescent reagents.

The enantiomneric separation and the detection of 2-arylpropionic acids after derivatization with the fluorescent reagents with a benzofurazan structure, (S)-(+)-4-(N,N- dimethylaminosulphonyl)-7-(3-aminopyrrolidin-1-yl)-2,1,3-ben zoxadiazole ((S)-DBD-Apy), (R)-(-)-4-nitro-7-(3-aminopyrrolidin-1-yl)-2,1,3- benzoxadiazole ((R)-NBD-Apy), 4-N,N-dimethylaminosulphonyl-7-piperazino-2,1,3-benzoxadi zole (DBD-PZ) and N-hydrazinoformylmethyl-N-methylamino-4,4- N,N-dimethylaminosulphonyl-2,1,3-benzoxadiazole (DBD-CO-Hz) by high-performance liquid chromatography (HPLC) and electrospray ionization mass spectrometry (ESI-MS) were examined. The diastereomeric derivatization with (S)-DBD-Apy or (R)-NBD-Apy and the separation on the reversed phase column afforded the high sensitivity. The separation on chiral stationary phase after non-chiral derivatization with DBD-PZ or DBD-CO-Hz provided less sensitivity. The signal-to-noise ratio of (S)-DBD-Apy-(S)-ketoprofen of 200:1 was observed for 12.5 picomole (pmol) injection and selected ion monitoring (SIM) of the quasi-molecular ion after splitting 1:7 before entering into the electrospray ion sources. As a result, the usefulness of these reagents for MS detection has been demonstrated.

Benzoxazoles↗
PubMedDate not supplied

Isolation and characterization of new porphyrin metabolites in human porphyria cutanea tarda and in rats treated with hexachlorobenzene by HPTLC, HPLC and liquid secondary ion mass spectrometry.

Porphyrin metabolisms in human porphyria cutanea tarda (PCT) and in rats treated with hexachlorobenzene (HCB) have been studied in detail by high performance thin layer chromatography (HPTLC), high performance liquid chromatography (HPLC) and liquid secondary ion mass spectrometry (LSIMS). The analyses of porphyrin metabolites in the urine, faeces and liver biopsies of patients with PCT have shown that apart from uroporphyrin I and III and their expected decarboxylation intermediates and products, a complex mixture of many other porphyrins are present. The new porphyrins identified are: meso-hydroxyuroporphyrin III, beta-hydroxypropionic acid uroporphyrin III, hydroxyacetic acid uroporphyrin III, peroxyacetic acid uroporphyrin III, beta-hydroxyproionic acid heptacarboxylic acid porphyrin III, hydroxyacetic acid hepatocarboxylic porphyrin III and peroxyacetic acid pentacarboxylic porphyrin III.

Animals↗
PubMedDate not supplied

Alcohol reduces the number of pheochromocytoma (PC12) cells in culture.

Pheochromocytoma (PC12) cells were used as an in vitro neuronal cell model to examine detrimental effects of alcohol on cell numbers. Alcohol exposure (100, 200, 400, and 800 mg/dl) reduced PC12 cell numbers in a dose-dependent manner. Cells that were treated with nerve growth factor (NGF) incurred less severe reductions in numbers compared with cells that were never treated with NGF. Because NGF stops proliferation of many of the PC12 cells and differentiates them into neuronal-like cells, these data suggest that differentiated, nonproliferating cells are less vulnerable to alcohol-induced reductions in cell numbers. In a subsequent experiment using only undifferentiated PC12 cells, alcohol reduced cell number of both proliferating and nonproliferating cultures; however, the reductions in proliferating cultures were more severe than in nonproliferating cultures. Two mechanisms may account for alcohol-induced reductions of PC12 cell numbers--inhibition of proliferation and killing of cells. PC12 cell cultures are a useful model system to examine mechanism(s) underlying alcohol's depletion of neuronal-like cells.

Animals↗
PubMedDate not supplied

CT volumetric data-based left ventricle motion estimation: an integrated approach.

This paper describes a novel approach to left ventricle motion analysis via the integration of image segmentation with shape deformation analysis using computerized tomography (CT) volumetric image data. This approach is different from traditional image analysis scenario in which the image segmentation and shape analysis were considered separately. The advantage of integrating the image segmentation with the shape analysis lies in the fact that the shape characteristics of the object can be used as effective constraints in the process of segmentation while original image data can be made useful along with the segmentation results in the process of shape analysis. In the case of left ventricle motion estimation, such an integration can be applied to obtain the estimation results that are consistent with both given image data and a priori shape knowledge. The initial segmentation of the images is obtained through adaptive K-mean classification and the region-of-interest is then identified based on the initial segmentation. The shape analysis is accomplished through fitting the boundary points of the region-of-interest to the surface modeling primitives. These two processes are integrated through the feedforward and feedback channels so that the surface fitting is constrained by the confidence measures of the boundary points and segmentation refinement is guided by the result of surface modeling. Global motion parameters are obtained by comparing the parameters of the fitted surface model at consecutive time instances. The segmentation and shape analysis results obtained show that the integrated approach is capable of providing promising improvement over traditional approaches.

Algorithms↗
PubMedDate not supplied

Cystic echinococcosis in semi-nomadic pastoral communities in north-west China.

In order to determine the prevalence of human cystic echinococcosis (CE) in semi-nomadic traditional pastoralist groups in north-west China, 2 large community studies were undertaken in Altai and Tacheng Prefectures in 1990/91 and 1995/96, respectively. The Kekergash community (Altai) comprised mainly ethnic Kazakhs, whereas the Narenhebuke community (Tacheng) comprised mainly Mongolians. Populations were screened for CE by abdominal ultrasound scan (US) and serological tests. The total prevalence of confirmed human CE was higher in Narenhebuke (2.7%, 49/1844) than in Kekergash (0.9%, 17/1861; P < 0.01). Within each community there was no significant difference of CE prevalence between the Kazakh and Mongolian groups, although Han Chinese exhibited twice the rate of CE (4.9%) in Narenhebuke compared to the dominant Mongolian population. For each community, human CE prevalence increased with age and there was a greater risk associated with the practice of home slaughter of livestock. Dogs were screened for Echinococcus granulosus infection and re-infection levels using a highly specific coproantigen test. The proportion of dogs with positive coproantigen tests was significantly higher in Narenhebuke (36.0%, 50/139) compared to Kekergash (17.8%, 16/90). In Narenhebuke the re-infection levels of dogs, as determined by coproantigen positivity, were higher in the winter quarters (49.4%, 39/79) compared to the summer quarters (18.3%, 11/60; P < 0.01). Furthermore, coproantigen re-test positivity was 25% at 3 months and 29.2% at 7 months. Highest dog coproantigen positivity was obtained over the winter period.

Adolescent↗
PubMedDate not supplied

Classification, follow-up and recurrence of hepatic cystic echinococcosis using ultrasound images.

Ultrasound image and morphological structure of hepatic cystic echinococcosis (CE) were analysed in 277 human cases (385 hepatic hydatid cysts). These included 65 CE cases from community surveys carried out between 1995 and 2000 in 3 countries (China, Mongolia and Jordan) and 212 cases from a clinical hospital survey from Xinjiang, China. A new simplified WHO ultrasound classification for human CE was assessed, and considered useful. It is proposed that type, size and number in particular need to be included in the ultrasound classification of hepatic CE. For comparative purposes 6 categories of type were classified in the study as Type 0 to Type 5 (T0-T5): T0, univesicular without pathognomonic signs; T1, univesicular with pathognomonic signs; T2, cysts with sagging or floating laminated membrane; T3, cysts containing daughter cysts; T4, solid mass or mixed cysts; and T5, cysts with partial or full calcifications. This differs from the WHO classification wherein Type T3 cysts (daughter cysts present) are considered a pathological stage to occur in general prior to the sagging or floating membrane (T2) stage. Recurrent hydatid cysts in the liver were also studied based on morphological structures observed directly from surgical intervention. Case follow-up over 1-5 years since endocystectomy in the community surveys indicated 10% (2/10) recurrence of cysts in the residual surgical cavity. Recurrent CE included 2 (2/4) cases after percutaneous treatment.

China↗
PubMedDate not supplied

Human aortic endothelial cell migration onto stent surfaces under static and flow conditions.

PURPOSE: The objective of the present study is to establish an in vitro model designed to quantitatively define human aortic endothelial cell (HAEC) migration onto stainless steel stent material under both static and flow conditions of high and low wall shear stress. MATERIALS AND METHODS: To simulate implantation of a stent onto the intact arterial wall, HAECs were seeded and grown to confluence on thick, firm collagen gels. Flat 1 x 1-cm square, stainless steel pieces were implanted on this endothelialized surface and migration of HAECs onto the steel surface was monitored, measured, and compared under static and high (15 dynes/cm2) and low (2 dynes/cm2) wall shear stress flow conditions designed to model wall shear stress levels encountered at different sites within the human arterial system. RESULTS: Under no flow, endothelial cell migration occurred uniformly from the periphery, attaining complete confluence over the square surface within 14 days. The initial migratory rate was approximately 10 micrograms/h +/- 0.5 days 1-3 and increased to a rate near 15 micrograms/h +/- 0.5 between days 10 and 14. High shear stress significantly (P < .002) increased HAEC migration rate to 25 micrograms/h +/- 0.8 in the direction of flow, resulting in an increase in total area endothelial coverage from 59% under no flow to 87% under high shear stress flow conditions when compared at 7 days. CONCLUSIONS: These results indicate the rate and extent of endothelial migration onto a prosthetic material surface are influenced by the level of direction of flow-related wall shear stress. Furthermore, these results demonstrate an in vitro model that provides a method to quantitatively evaluate and possibly predict the relative ability of different prosthetic materials to endothelialize under variable in vivo flow conditions.

Angioplasty↗
PubMedDate not supplied

Design and synthesis of [111In]DTPA-folate for use as a tumor-targeted radiopharmaceutical.

Folate-conjugated metal chelates have been proposed as potential imaging agents for cancers that overexpress folate receptors. In a previous study, folic acid was linked through its gamma-carboxyl group to deferoxamine (DF), and the 67Ga-labeled complex ([67Ga]DF-folate) was examined for in vivo tumor targeting efficiency in athymic mice with a human tumor cell implant. Although superb tumor-to-background contrast was obtained, slow hepatobiliary clearance would compromise imaging of abdominal tumors such as ovarian cancer. In the present study, folic acid was conjugated to an alternative chelator, diethylenetriaminepentaacetic acid (DTPA), via an ethylenediamine spacer. The desired DTPA-folate (gamma) regioisomer was synthesized by two different approaches, purified by reversed phase column chromatography, and characterized mainly by analytical HPLC, mass spectroscopy, and NMR. In cultured tumor cells, uptake of [111In]DTPA-folate (gamma) was found to be specific for folate receptor-bearing cells, and the kinetics of uptake were similar to those of free folate and other folate-conjugated molecules. In the normal rat, intravenously administered [111In]DTPA-folate (gamma) was found to be rapidly excreted into the urine, giving intestinal levels of radiotracer 10-fold lower than those observed with [67Ga]DF-folate (gamma) at 4 h. In a preliminary mouse imaging study, a folate receptor-positive KB cell tumor was readily visualized by gamma scintigraphy 1 h following intravenous administration of [111In]DTPA-folate (gamma).

Animals↗
PubMedDate not supplied

Kinetics of simultaneous saccharification and lactic acid fermentation processes.

After pretreatment of corn cob by dilute acid, the lignocellulosic residue was used as raw materials for the simultaneous saccharification and lactic acid fermentation (SSLF). Because of the same optimal temperature and pH requirement as well as the anaerobic condition, the lactic acid fermentation is perfectly compatible with enzymatic hydrolysis of cellulosic materials. In the SSLF processes, the final concentration of lactic acid reached 33.97 g/L with a conversion ratio of 79% based on the consumed cellulose. A mathematical model is suggested to simulate the SSLF process with good agreement.

Adsorption↗
PubMedDate not supplied

Peripheral neurologic abnormalities among roofing workers: sentinel case and clinical screening.

Peripheral neuropathy developed in a 52-y-old roofer who was exposed to multiple solvents in one-ply roofing systems. Forty roofers who were exposed to various roofing systems were assessed by symptoms, occupational history, standardized physical examination, and measurement of vibrotactile thresholds of the upper and lower extremities. After exclusion of roofers who were predisposed to peripheral neuropathy, we detected abnormal vibrotactile thresholds in 42% (p < .001) of roofers' dominant toes and in 36% (p < .001) of roofers' nondominant toes; fewer roofers had abnormal sensory physical examinations or reported neuritic symptoms. Roofing workers may be at increased risk of peripheral neuropathy, perhaps resulting from exposure to solvents--particularly n-hexane, associated with one-ply roofing systems.

Construction Materials↗
PubMedDate not supplied

PM-3, a benzo-gamma-pyran derivative isolated from propolis, inhibits growth of MCF-7 human breast cancer cells.

Propolis has numerous biologic activities including antibiotic, antifungal, antiviral and anti-inflammatory properties. Several components isolated from propolis have been shown to have anticancer activity. This study demonstrates that the compound PM-3 (3-[2-dimethyl-8-(3-methyl-2-butenyl)benzopyran]-6-propenoic acid) isolated from Brazilian propolis markedly inhibits the growth of MCF-7 human breast cancer cells. This effect was associated with inhibition of cell cycle progression and induction of apoptosis. Treatment of MCF-7 cells with PM-3 arrested cells in the G1 phase and resulted in a decrease in the protein levels of cyclin D1 and cyclin E. PM-3 also inhibited the expression of cyclin D1 at the transcriptional level when examined in cyclin D1 promoter luciferase assays. Induction of apoptosis by PM-3 occurred within 48 hours after treatment of MCF-7 cells. The MCF-7 treated cells also displayed a decrease in the level of the estrogen receptor (ER) protein and inhibition of estrogen response element (ERE) promoter activity. Therefore, PM-3 merits further investigation with respect to breast cancer chemoprevention or therapy.

Annexin A5↗