Biomedical subjects
Publications and source records attributed to H Luo.
Penetrating aortic ulcers and intramural hematomas cannot always be differentiated by transesophageal echocardiography. We suggest that color and pulsed-wave Doppler flow can be used for identifying penetrating aortic ulcers.
Intravascular ultrasound demonstrated plaque ruptures that occurred in regions involved with large complicated atherosclerotic plaques in the coronary artery. Because intravascular ultrasound evaluates both plaque and luminal dimensions, it contributes to our understanding of the pathophysiology of coronary artery disease.
The 78-kDa glucose-regulated protein (GRP78) is localized in the endoplasmic reticulum (ER), and its expression is increased by environmental stressors in many types of nonneuronal cells. We report that levels of GRP78 are increased in cultured rat hippocampal neurons exposed to glutamate and oxidative insults (Fe2+ and amyloid beta-peptide) and that treatment of cultures with a GRP78 antisense oligodeoxynucleotide increases neuronal death following exposure to each insult. GRP78 antisense treatment enhanced apoptosis of differentiated PC12 cells following NGF withdrawal or exposure to staurosporine. Pretreatment of hippocampal cells with 2-deoxy-d-glucose, a potent inducer of GRP78 expression, protected neurons against excitotoxic and oxidative injury. GRP78 expression may function to suppress oxidative stress and stabilize calcium homeostasis because treatment with GRP78 antisense resulted in increased levels of reactive oxygen species and intracellular calcium following exposure to glutamate and oxidative insults in hippocampal neurons. Dantrolene (a blocker of ER calcium release), uric acid (an antioxidant), and zVAD-fmk (a caspase inhibitor) each protected neurons against the death-enhancing action of GRP78 antisense. The data suggest that ER stress plays a role in neuronal cell death induced by an array of insults and that GRP78 serves a neuroprotective function.
OBJECTIVES: To validate intravascular ultrasound (IVUS) measurements for differentiating functionally significant from nonsignificant coronary stenosis. BACKGROUND: To date, there are no validated criteria for the definition of a flow-limiting coronary artery stenosis by IVUS. METHODS: Preinterventional IVUS imaging (30-MHz imaging catheter) of 70 de novo coronary lesions was performed. The lesion lumen area and three IVUS-derived stenosis indixes comparing lesion lumen area with the lesion external elastic lamina (EEL) area, the mean reference lumen area and the mean reference EEL area were compared with the results of stress myocardial perfusion imaging. RESULTS: The lesion lumen area and three IVUS-derived stenosis indexes showed sensitivities and specificities ranging between 80% and 90% using stress myocardial perfusion imaging as the gold standard. The lesion lumen area < or =4 mm2 is a simple and highly accurate criterion for significant coronary narrowing. CONCLUSIONS: Quantitative IVUS indices can be reliably used for identifying significant epicardial coronary artery stenoses.
The purpose of this study was to evaluate the modification of the saline echo contrast method by mixing blood with agitated saline before intravenous injection. In 20 patients, contrast echocardiography was performed with a conventional technique from the apical 4-chamber view. We used 2 techniques: (1) the combination of blood (1 mL) withdrawn from the patients and air-agitated saline agitated, (2) air-agitated. In all patients, the blood combination technique was judged to make a greater contrast, with the agreement of all 3 reviewers. Peak echo intensity of the right ventricular cavity by the blood combination technique was significantly higher than that by agitated saline alone. In conclusion, the use of the combination of blood and agitated saline is superior to agitated saline alone for the opacification of the right atrium and ventricle in routine echocardiography.
Ultrasonic thrombolysis has been proved to be an efficient and safe modality for the treatment of acute arterial occlusions in vitro and in vivo in animal studies. There have been and are ongoing parallel improvements in ultrasound technology and adjuvant pharmacological treatments for therapeutic applications. Thus therapeutic ultrasound for thrombolysis holds great promise in overcoming the limitations of current available therapies.
1,2-Palmitoyl-3-[15-(4-iodophenyl)pentadecan-3-oyl]-rac-glycerol (MIPAG) is a new agent for the clinical evaluation of pancreatic lipase activity and has demonstrated promise in preliminary clinical studies with patients affected with pancreatic insufficiency. Iodine-131-MIPAG was initially prepared via thallium-iodide displacement. Because of the need for a simple method which is amendable for the routine clinical use of MIPAG we have investigated the preparation and radioiodination of MIPAG utilizing the tributyltin precursor, 1,2-palmitoyl-3-[15-(4-tributylstannylphenyl)pentadecan-3-oy l]-rac-glycerol (TBT-MIPAG, 2). Compound 2 was prepared via the condensation of 1,2-palmitoyl-rac-glycerol with 15-(4-tributylstannylphenyl)pentadecanoic acid (TBT-PPA) prepared from 4-bromophenylacetylene. Electrophilic radioiodination using peracetic acid with sodium iodide-125 in ethanol at 80 degrees C for 60 min afforded I-125-MIPAG in 65.9% (+/- 11.5%) yield and radiochemical purity of 94% (+/- 3.0%) after C-18 Sep-Pak purification (n = 6). This improved method for radioiodination utilizing TBT-MIPAG now provides radioiodinated MIPAG for routine clinical evaluation.
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Thirty-four women bearing a levonorgestrel-releasing intrauterine device, 20 micrograms/day (LNG-IUD-20), for 12-15 months were recruited. Endometrial biopsies were collected during the late proliferative phase of the cycle (on cycle days 10-12) before (control) and after the use of the IUD for 12 months, and assayed for oestrogen receptors (ER) and progesterone receptors (PR). An immunohistochemical technique with the peroxidase-antiperoxidase detection system (PAP method) was employed. D75 and JZB39 were the primary antibodies for ER and PR respectively. The immunostaining semiquantitative analysis was performed with a computerized microscope image processor, and expressed as 'grey value'. Both endometrial ER and PR populations were significantly lower after insertion of the IUD (P < 0.01) than in control biopsies. The intensity of nuclear staining and the percentage of positively stained cells for ER and PR in women with LNG-IUD were each about 50% of those in control biopsies. The results suggested that LNG released locally from the IUD has a depressive action on the ER and PR, which may contribute to the contraceptive effectiveness of this type of IUD and also to the possible causes of LNG-IUD-induced irregular bleeding and amenorrhoea.
The proton-pumping ATPase (H+-ATPase) of the plant plasma membrane is encoded by two major gene subfamilies. To characterize individual H+-ATPases, PMA2, an H+-ATPase isoform of tobacco (Nicotiana plumbaginifolia), was expressed in Saccharomyces cerevisiae and found to functionally replace the yeast H+-ATPase if the external pH was kept above 5.0 (A. de Kerchove d'Exaerde, P. Supply, J.P. Dufour, P. Bogaerts, D. Thinès, A. Goffeau, M. Boutry [1995] J Biol Chem 270: 23828-23837). In the present study we replaced the yeast H+-ATPase with PMA4, an H+-ATPase isoform from the second subfamily. Yeast expressing PMA4 grew at a pH as low as 4.0. This was correlated with a higher acidification of the external medium and an approximately 50% increase of ATPase activity compared with PMA2. Although both PMA2 and PMA4 had a similar pH optimum (6.6-6.8), the profile was different on the alkaline side. At pH 7.2 PMA2 kept more than 80% of the maximal activity, whereas that of PMA4 decreased to less than 40%. Both enzymes were stimulated up to 3-fold by 100 microgram/mL lysophosphatidylcholine, but this stimulation vanished at a higher concentration in PMA4. These data demonstrate functional differences between two plant H+-ATPases expressed in the same heterologous host. Characterization of two PMA4 mutants selected to allow yeast growth at pH 3.0 revealed that mutations within the carboxy-terminal region of PMA4 could still improve the enzyme, resulting in better growth of yeast cells.
OBJECTIVE: To estimate the effect of an intrauterine device (IUD) releasing 20 micrograms levonorgestrel (LNG) per 24 hours on DNA synthesis in human endometrial cells before and after 12 months of use. STUDY DESIGN: Endometrial specimens were collected from the anterior or posterior wall of the miduterus from 6 females on cycle day 10-12 before insertion of the IUD and after 12 months of use. RESULTS: Previous results from our group did not reveal any influence on endometrial DNA cell content when a levonorgestrel IUD releasing 2 micrograms/24 h was used for 12 months in a group of fertile females. In this study, the IUD release rate, 20 micrograms LNG/24 h, was statistically significantly different from the results in the previous studies. The effect of the levonorgestrel IUD on endometrial proliferation was dose dependent, and a significant correlation could be found between continuous exposure to LNG and inhibition of DNA synthesis in endometrial cells. CONCLUSION: Inhibition of proliferative activity in endometrial cells seems to be reflected by a decrease in DNA synthesis per cell nucleus and contributes to the clinical performance of the LNG-releasing IUD.
UNLABELLED: Biodistribution studies with the radioiodinated 3(R)- and 3(S)-isomers of 15-(p-iodophenyl)-3-methylpentadecanoic acid (BMIPP) in rats have shown that 3(R)-BMIPP has 20%-25% higher heart uptake than 3(S)-BMIPP (15-180 min). In contrast, the 3(S)-isomer has slightly higher liver uptake, and uptake in other tissues examined is similar. METHODS: To evaluate the possible differences in metabolic fate of the two isomers, a mixture of [125I]-3(R)/[131I]-3(S)-BMIPP was administered to fasted female Fisher rats. Groups of rats (3 per group) were killed 15, 60 and 180 min after administration. Urine and feces were collected from a fourth group (n = 3) over 7 d. Samples of blood, heart, liver, lungs, kidney and urine were Folch extracted. The distributions of 125I and 131I in the organic (lipid), aqueous and pellet samples were determined. The lipid samples as well as the organic fractions from base-hydrolyzed triglyceride (TG) fractions and acid-hydrolyzed urine samples were then analyzed by thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC). RESULTS: The relative distributions of 125I and 131I in the lipid, aqueous and pellet samples were similar for both isomers. Distribution of 125I and 131I in the various components of the lipid extracts observed by TLC (hexane:ether:HOAc, 70:30:1) was also similar, with principal incorporation into the free fatty acid (FFA) and TG pools. HPLC analyses (C18) of the FFA fraction showed similar 125I and 131I profiles, corresponding to BMIPP, and the alpha-methyl-C14 (14-(p-iodophenyl)-3-(R,S)-methyltetradecanoic acid) and C12, C10 and C6 carbon chain-length catabolites. By TLC, radioactive components of 125I and 131I in the urine had the same TLC mobility as hippuric acid. HPLC analyses (C18) of acid-hydrolyzed urine gave a single 125I/131I component with the same relative retention time as 2-(p-iodophenyl)acetic acid, which is the final alpha/beta-oxidative BMIPP catabolite. Unexpectedly, HPLC of lipids from base-hydrolyzed TG from the heart tissue showed 125I/131I components with the same retention times as shorter-chain fatty acids, similar to the FFA fraction, with only low levels of activity detected in BMIPP. CONCLUSION: These results show that 3(R)-BMIPP and 3(S)-BMIPP are metabolized similarly in rat tissues and that higher myocardial extraction observed for 3(R)-BMIPP may reflect differences in the relative membrane transport of the two isomers.
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This study was aimed at the relationship between anaerobes and clinical infection. Aerobic and anaerobic bacterial culture was performed for 436 specimens of clinical infection. The incidence of anaerobic bacteria isolates and predominant species were analyzed. The results showed that the incidence of anaerobic isolates was 88.3% (385/436), the main predeminoue species were Gram negative nonsporeforming anaerobic rods (Bacteroids, Prevotella and Porphyromonas) and peptostreptococcus. The endogenous infection, caused by anaerobic microflora of human body as the main pathogens, and the mixed bacterial infection are the most common feature of human clinical anaerobic infections.
OBJECTIVE: To separate compounds from the root of Gypsophila oldhamiana. METHOD: Chemical and chromatographic methods were used to separate the compounds. IR, MS, NMR were used to determine the structures of compounds. RESULT: Compound pentacosanoic acid, lacceroic acid, beta-sitosterol, alpha-spinasterol, daucosterol and sucrose were identified. CONCLUSION: All the above compounds were obtained from this genus for the first time.
OBJECTIVE: To isolate and purify salivary histidine-rich-polypeptides (HRPs) and observe their antibacterial activities. METHODS: By using of preparative acid urea polyacrylamide gel electrophoresis (AU-PAGE), three major HRPs(HRP-1, HRP-3 and HRP-5) were purified from parotid saliva collected from healthy adults. Their antibacterial activities were tested in the ultrasensitive antibacterial assay, named radial diffusion assay. RESULTS: Each fraction of the three purified HRPs appeared as a single protein zone both in AU-PAGE and Tricine-SDS-PAGE. Their molecular weights are 3-5 kD as determined by Tricine-SDS-PAGE. All the three major HRPs showed potent bactericidal effects on Streptococcus mutans MT6R and Staphylococcus aureas ATCC25923. As to Escherichia coli ML-35P and Pseudomonas aeruginosa ATCC27853, HRP-3 and HRP-5 also demonstrated significant antibacterial activities, whereas HRP-1 did not show any inhibitory effects on the viability of them. CONCLUSION: The above results suggested that the method of preparative AU-PAGE we used in this study has the benefits of high resolution, simple manipulation and perfect results of purification. HRPs are important components to prevent oral tissue from bacterial infections, therefore play a potent role in the maintenance of the oral health.
Two additives, phenol, 2,6-bis(1,1-dimethylethyl)-4-methyl- and triphenyl phosphate with mass ratio of less than one thousandth in special super-high pressure hydraulic oil were determined by GC-MS. Tributyl phosphate ester was used as internal standard. The correction factor of each additive was determined before analysis. Each sample was analysed for 5 times to get good precision. It is satisfactory to use SIM as the detecting mode, and the CVs of correction factors and mass ratio were about 5%. The problems of how to select the monitoring ion in SIM mode and the sample size required are discussed in this paper. This method is satisfactory in analyzing low mass ratio constituents in a mixture.
The ZRT1 gene encodes the transporter responsible for high affinity zinc uptake in yeast. ZRT1 is transcribed in zinc-limited cells and its transcription is repressed in zinc-replete cells. In this report, we describe a second, post-translational mechanism that regulates ZRT1 activity. In zinc-limited cells, ZRT1 is a stable, N-glycosylated plasma membrane protein. Exposure to high levels of extracellular zinc triggers a rapid loss of ZRT1 uptake activity. Our results demonstrate that this inactivation occurs through zinc-induced endocytosis of the protein and its subsequent degradation in the vacuole. Mutations that inhibit the internalization step of endocytosis also inhibited zinc-induced ZRT1 inactivation and the major vacuolar proteases were required to degrade ZRT1 in response to zinc. Furthermore, immunofluorescence microscopy showed that ZRT1 is localized to the plasma membrane in zinc-limited cells and that the protein is transferred to the vacuole via an endosome-like compartment upon exposure to zinc. ZRT1 inactivation is a relatively specific response to zinc; cadmium and cobalt ions trigger the response but less effectively than zinc. Moreover, zinc does not alter the stability of several other plasma membrane proteins. Therefore, zinc-induced ZRT1 inactivation is a specific regulatory system to shut off zinc uptake activity in cells exposed to high extracellular zinc levels thereby preventing overaccumulation of this potentially toxic metal.