Biomedical subjects

J Ye

Publications and source records attributed to J Ye.

At least 181 records · Page 10Linked to original sources

PubMed1998

[Study on the epidemiological characteristics and strategy of surveillance in low endemic areas of malaria in Hubei].

Due to good programs on case finding and control, malaria has decreased to a low level in China. Hence, the existing surveillance program of undertaking blood smear from cases with fever finds very few positives in the millions of examinees. Previously, all blood slides were collected from clinically diagnosed cases of malaria (group 1), suspected malaria cases (group 2), fever of unknown reasons (group 3) or common cold (group 4) in low or moderate malaria endemic areas in Hubei Province. In low prevalence areas, the positive rates on slides were 0.6/10,000 and 0.1/10,000 in group 3 and group 4 while 95.38% of the confirmed malaria cases were from those having clinical malaria or suspected malaria. It is suggested that group 3 and group 4 be dropped from low prevalence areas to encourage greater efficiency in case detection in the clinical and the suspected malaria groups.

Animals↗

PubMed1998

Long-term studies on allotransplantation of rabbit retinal pigment epithelial cells double-labelled with 5-bromodeoxyuridine and natural pigment.

OBJECTIVE: To facilitate the identification of transplanted retinal pigment epithelial (RPE) cells, we sought to double-label the cells with 5-bromodeoxyuridine (BrdU) and with natural pigment. The BrdU is not lost during cell division but does require immunohistochemical methods for visualization; the pigment on the other hand, allows immediate, obvious identification, but is gradually lost with cell division. Together they provide a convenient, long-term double label. METHODS: Non-confluent RPE cells at the second to the fifth passages were labelled with 5-BrdU and pigment. The double-labelled RPE cells were transplanted onto Bruch's membrane of 72 eyes of New Zealand albino rabbits. The labelled cells were localized by anti-BrdU antibody and the avidin biotin-alkaline phosphatase complex (ABC-AP) method, and by visible inclusions of pigment. RESULTS: The transplanted RPE cells had distinct basal and apical morphology, and were in close contact with the photoreceptor outer segments of the host. The BrdU label was restricted to the nuclei of the RPE cells, which were stained blue. The pigment was located in the cytoplasm of the apical portion of these RPE cells. No evidence of severe rejection was seen. CONCLUSIONS: Using this double-label method, transplanted RPE cells could be readily and reliably identified till one year after transplantation. The transplanted RPE cells revealed normal morphology with some function: they had distinct basal and apical morphology as seen in close contact with the outer segment of photoreceptor cells. The junctional complexes were well formed with neighboring RPE cells. The transplanted RPE cells phagocytose shed outer segments of the host. No evidence of rejection was observed, suggesting that the subretinal space of the rabbit may possess some degree of immunologic privilege. This experiment provides reliable evidence for the clinical research of allotransplantation of RPE cells.

Affinity Labels↗

PubMed1998

[Application of MVR-PCR at D1S8 locus with HRP-labeled MS32 oligonucleotides probes].

The purpose of this study is to detect small amount of biological materials using the method of MVR-PCR at D1S8 locus with HRP-labeled MS32 oligonucleotides probe. The results showed that the MVR-PCR patterns, obtained from trace blood stain (equal to 5 ul blood), trace saliva stain (equal to 4 ul saliva) or a hair root, can be read clearly and easily. The sensitivity of the method is 1 ng DNA. The applications of the method in personal identification were discussed.

Blood Stains↗

PubMed1998

[Extra-anatomy axillary-femoral or femoro-femoral bypass grafting for the treatment of aorta-iliac occlusive disease].

OBJECTIVE: To study the result of extra-anatomy axillary-femoral or femoro-femoral bypass grafting which was performed to treat aorta-iliac arterial occlusive disease. METHOD: From 1978 through 1997, 32 patients with aorta-iliac occlusive disease underwent extra-anatomy axillary-femoral or femoro-femoral bypass grafting at our hospital. Eighteen patients with aorta or bilateral iliac artery occlusive lesion underwent axillary-femoral artery bypass, including axillary-bifemoral artery bypass (2 patients). Fourteen patients with one side iliac arterial occlusive lesion received femoro-femoral bypass grafting. In who had had axillary-femoral artery bypass 18 patients, 8 received, pure silk prosthesis, and 10 Gore-Tex prosthesis. In femoro-femoral arterial bypass, pure silk prosthesis was given to 8 patients, saphenous vein to one, and Gore-Tex prosthesis to 7. RESULT: Follow-up for 5 years, a patency rate of 78% was achieved in femoro-femoral artery bypass, in which no different patency rate was found between pure silk prosthesis and Gore-Tex prosthesis. In axillary-femoral bypass, eight pure silk prostheses were occluded after 5-year follow-up. One of 10 Gore-Tex prostheses was occluded, and false aneurysm in groin was found in another patient. CONCLUSION: This operation is easy and safe, it has less damage and no abdominal complication. The recovery of the patient is quick. Pure silk prostheses are only used in short segment femoro-femoral bypass grafting.

Adult↗

PubMed1998

[The time-frequency analysis of the exercise ECG signal].

Exercise ECG indicates information about the heart load status in the exercise test. It is very significant to represent the characteristics of the exercise ECG for evaluating the exercise load test. This article introduces the principle of Winger-Ville Distribution time-frequency analysis and its implementation. By applying this method to analyse exercise ECG, some results were acquired. It is a promising method to do research of the exercise ECG in the time-frequency plane.

Algorithms↗

PubMed1998

[Studies on the selection of strains producing colominic acid and culture conditions].

One strain E. coli C-8, the highest yield of colominic acid, was selected from 40 E. coli strains in the medium in which glucose and ammonium sulfate were the only carbon and nitrogen resources. An optimum medium for the growth and colominic acid production of E. coli C-8 was studied. The optimum carbon resources for colominic acid production was sorbitol selected from 16 kinds of carbons, and its optimum concentration was 2.5%. The optimum inorganic and organic nitrogen resources for colominic acid production were ammonium sulfate (0.5%) and tryptone (1.5%), respectively. The optimum concentration of K2 HPO4 was 90 mmol/L. The optimum culture temperature was 37 degrees C, but no colominic acid was produced below 20 degrees C. The optimum pH range was 7.5-8.2. The strain growth in the optimum medium kept logarithmic phase in 40 h (maxim A = 22). The colominic acid secreted into medium was much lower before 20 h, but high biosynthetic rate of colominic acid was detected after 40 h, the colominic acid reached the highest level (1,200 micrograms/ml) at 65 h.

Culture Media↗

PubMed1998

[Fluorescence emission spectra of petroleumsulfonate and OP-10 in multi-components aqueous solutions].

The determination of surfactant(s) in the alkaline/surfactant/polymer flooding solutions was an uneasy job. For this purpose, the method of fluorescence emission by phenoxy-containing surfactants in dilute solutions is suggested. The fluorescence emission intensity changes linearly with in the extent of low surfactant concentrations below the critical micelle concentration (CMC) and is not influenced by the presence of alkali, polymer PHPAM and salts. Under certain conditions the fluorescence emission by petroleum sulfonate and OP-10 in a multi-components aqueous solution can be detected independently. This method is high-selective, sensitive (the lowest detectable concentration 10(-7) mol/L) and microanalytical (the amount of test solution 2-3 microL).

English Abstract↗

PubMed1997

Does retrograde warm blood cardioplegia provide equal protection to both ventricles? A magnetic resonance spectroscopy study in pigs.

BACKGROUND: The degree of protection provided to the right ventricle during retrograde continuous normothermic blood cardioplegia (RCNBC) remains controversial. The purpose of this study was to determine whether RCNBC is able to provide "adequate" nutritive flow to both ventricles to prevent ischemic metabolism in normal swine hearts. Localized 31P magnetic resonance spectroscopy (MRS) was used to monitor the changes in energy metabolism and intracellular pH (pHi) in each ventricle separately. METHODS AND RESULTS: Isolated normal swine hearts received 20 minutes of antegrade continuous normothermic blood cardioplegia (ACNBC) for collection of control (baseline) data, followed by 20 minutes of RCNBC. This protocol was repeated four times in five hearts and twice in two hearts. Perfusion pressure was maintained between 70 to 85 and 38 to 43 mm Hg during ACNBC and RCNBC, respectively. pHi, creatine phosphate (PCr), inorganic phosphate (Pi), and ATP were measured continuously in each ventricle during ACNBC and RCNBC, using localized 31P MRS with two surface coils. RCNBC resulted in a significant increase in Pi (LV 222% and RV 244% of the baseline levels, respectively) and a decrease in PCr (left ventricle [LV] to 68% and right ventricle [RV] to 31% of the baseline levels, respectively) in both ventricles relative to ACNBC. The PCr level was significantly lower in the RV than in the LV (31% versus 68%, P<.001) during RCNBC. In one series of experiments (n=5) where ACNBC and RCNBC were alternated every 20 minutes (ACNBC, RCNBC, ACNBC, RCNBC, ACNBC) for a total of 100 minutes, Pi and PCr recovered completely. A continuous and significant decrease in ATP was observed in the RV, and no recovery of ATP was found when switching from RCNBC to ACNBC. No significant decrease in ATP was observed in the LV. pHi remained unchanged in both ventricles during alternate ACNBC and RCNBC. CONCLUSIONS: Energy metabolism in the RV is less well preserved than in the LV during RCNBC. A combination of ACNBC and RCNBC seems to provide good cardiac protection as measured by the recovery of cardiac energetics and pHi.

Adenosine Triphosphate↗

PubMed1997

Influence of Arginines 93, 97, and 101 of thrombin to its functional specificity.

Mutation of three Arg residues, 93, 97, and 101, to Ala in thrombin (thrombin R93,97,101A) has previously been shown to eliminate most heparin acceleration of thrombin inhibition by antithrombin and most of the ability of chondroitin sulfate (CS) on thrombomodulin (TM) to enhance affinity for TM and to eliminate the characteristic high-affinity interaction with protein C observed with TM lacking CS. In this study we examined the relative impact of mutation of these Arg residues alone and in combination on the above reactions and, in addition, on the ability of rabbit TM to accelerate thrombin inhibition by antithrombin. The order of importance for heparin acceleration of inhibition by antithrombin was Arg 101, 93, and 97. In contrast, Arg 97 was the major residue required for TM-dependent acceleration of reactivity with antithrombin and for CS-dependent enhancement of TM affinity. Arg 101 and 93 were critical for TM-dependent, high-affinity protein C interaction at low Ca2+ concentrations, while Arg 97, which was critical for the other TM-dependent effects, played no detectable role in this metal dependence. These results illustrate that these Arg residues in anion binding exosite 2 contribute very differently to the diverse reactions dependent on that domain in thrombin.

Animals↗

PubMed1997

The fate of cholesterol exiting lysosomes.

Cholesterol released from ingested low density lipoproteins in lysosomes moves both to the plasma membrane and to the endoplasmic reticulum (ER) where it is re-esterified. Whether cholesterol can move directly from lysosomes to ER or first must traverse the plasma membrane has not been established. To examine this question, the endocytic pathway of rat hepatoma cells was loaded at 18 degrees C with low density lipoproteins (LDL) labeled with [3H]cholesteryl linoleate, and the label then was chased at 37 degrees C. The hydrolysis of the accumulated ester proceeded linearly for several hours. Almost all of the released [3H]cholesterol moved to the plasma membrane rapidly and without a discernable lag. In contrast, the re-esterification in the ER of the released [3H]cholesterol showed a characteristic lag of 0.5-1 h. These data are inconsistent with direct cholesterol transfer from lysosomes to ER; rather, they suggest movement through the plasma membrane. Furthermore, we found that progesterone, imipramine and 3-beta-[2-(diethylamino)ethoxy]androst-5-en-17-one (U18666A) strongly inhibited the re-esterification of lysosomal cholesterol in the ER. However, contrary to previous reports, they did not block transfer of [3H]cholesterol from lysosomes to the cell surface. Therefore, the site of action of these agents was not at the lysosomes. We suggest instead that their known ability to block cholesterol movement from the plasma membrane to the ER accounts for the inhibition of lysosomal cholesterol esterification. These findings are consistent with the hypothesis that cholesterol released from lysosomes passes through the plasma membrane on its way to the ER rather than proceeding there directly. As a result, ingested cholesterol is subject to the same homeostatic regulation as the bulk of cell cholesterol, which is located in the plasma membrane.

Adrenergic Uptake Inhibitors↗

PubMed1997

One-electron reduction of chromium(VI) by alpha-lipoic acid and related hydroxyl radical generation, dG hydroxylation and nuclear transcription factor-kappaB activation.

Reaction of chromium(VI) with alpha-lipoic acid (reduced form, also called 1,2-dithiolane-3-pentanoic acid) generated Cr(V) and hydroxyl radical (*OH) as measured by electron spin resonance and ESR spin trapping. 5,5-Dimethyl-1-pyrroline was used as a spin trapping agent. Catalase inhibited the *OH generation and enhanced the Cr(V) formation. Superoxide dismutase had an opposite effect. H2O2 enhanced the *OH generation and decreased the Cr(V) formation in a dose-dependent manner. Metal chelators, EDTA, diethylenetriaminepentaacetic acid, deferoxamine, and 1, 10-phenanthroline inhibited *OH radical generation in the order of EDTA > 1,10-phenanthroline > DTPA > deferoxamine. Oxygen consumption measurements indicated that molecular oxygen was used to generate *OH radical in the mixture of Cr(VI) and alpha-lipoic acid. H2O2 and superoxide radical (O2-) were involved as reactive intermediates. The *OH radical was generated via Cr(V)-mediated Fenton-like reaction (Cr(V) + H2O2 --> Cr(VI) + OH- + *OH). HPLC measurements show that the *OH radical generated by this reaction is capable of generating 8-hydroxyl-2'-deoxyguanosine from 2-deoxyguanosine. Incubation of Cr(VI) with cultured Jurkat cells resulted in an activation of DNA binding activity of the nuclear factor (NF)-kappaB. Addition of alpha-lipoic acid enhanced the NF-kappaB activation, while the *OH radical scavenger, sodium formate, inhibited it, showing that alpha-lipoic acid enhanced Cr(VI)-induced NF-kappaB activation via free radical reactions. The results indicate that while alpha-lipoic acid is considered to be an antioxidant, it may be a cellular one-electron Cr(VI) reductant and could be involved in the mechanism of Cr(VI)-induced carcinogenesis.

Antioxidants↗

PubMed1997

The effect of circulatory arrest and retrograde cerebral perfusion on microtubule-associated protein 2: an immunohistochemical study in pig hippocampus.

Microtubule-associated protein 2 (MAP2) immunohistochemical labeling in the hippocampus was studied to assess the protective effect of brain perfusion during surgery requiring hypothermic circulatory arrest in 24 pigs exposed to anesthesia alone (control), 120 min of complete circulatory arrest at 15 degrees C, min of retrograde cerebral perfusion at 15 degrees C, or 120 min of anterograde cerebral perfusion at 15 degrees C. Pigs were reperfused for 60 min and sacrificed. In the control anterograde perfusion groups, the intensity of MAP2 labeling was similar in all regions of the hippocampus. Circulatory arrest and retrograde perfusion resulted in significant reduction of MAP2 labeling (28% and 38% respectively of control, P < 0.001) of neurons in the CA1 region. MAP2 labeling may be useful for assessing early damage in the hippocampus in this model.

Animals↗

PubMed1997

Beyond hyperkalemia: beta-blocker-induced cardiac arrest for normothermic cardiac operations.

BACKGROUND: Four experimental protocols were carried out to assess the ability of esmolol to induce and maintain reversible cardiac arrest under continuous normothermic (37 degrees C) perfusion. METHODS AND RESULTS: In the first protocol, 8 perfused rat hearts were subjected to 20, 60, 90, and 120 minutes of esmolol arrest, after which positive and negative first derivative of pressure, heart rate, left ventricular developed pressure, and left ventricular end-diastolic pressure were evaluated. Arrest was achieved 45 to 60 seconds after beginning the infusion of esmolol. Mechanical arrest was achieved before electrical arrest. In the second protocol, dose-response curves were obtained using isolated (Langendorff) rat and rabbit (n = 6) hearts. The concentrations of esmolol varied from 0.084 to 6.7 mmol/L and from 0.12 to 1.45 mmol/L in the rat and rabbit heart experiments, respectively. In the third protocol, the effects of 20 minutes of normothermic (37 degrees C) ischemia on the function of isolated rat hearts perfused with esmolol-containing Krebs solution were compared with those using high-potassium (25 mmol/L) Krebs solution. Group A subjects (n = 9) received the ischemic injury after being perfused (and arrested) for 20 minutes with either esmolol or potassium (KCl, 25 mmol/L). Group B subjects (n = 10) received the same ischemic insult before being perfused with either esmolol or potassium. Esmolol-treated hearts showed better recovery than those receiving potassium, in terms of +/- dP/dt (p < 0.01), left ventricular systolic pressure (p < 0.01), and left ventricular developed pressure (p < 0.009). Finally, the fourth protocol was done to evaluate the effects of esmolol in a clinically relevant experimental model. Pigs were divided into esmolol (n = 6) and potassium (n = 5) groups and subjected to normothermic cardiopulmonary bypass and a 1-hour period of cardiac arrest. Twenty minutes after stopping infusion of the cardioplegic agents, all animals were weaned off bypass. There were no statistically significant differences between the groups. CONCLUSIONS: Esmolol hydrochloride can be used as effectively as potassium for inducing and maintaining predictable and reversible cardiac arrest during normothermic cardiac operations.

Adrenergic beta-Antagonists↗

PubMed1997

Retrograde cerebral perfusion provides limited distribution of blood to the brain: a study in pigs.

OBJECTIVE: The objective of this study was to investigate flow distribution during retrograde and antegrade cerebral perfusion with India ink as a marker. METHODS: Ten pigs received cerebral perfusion with a solution containing 50% filtered India ink for 5 minutes either antegradely through both internal carotid arteries at a flow of 180 to 200 ml/min (n = 5) or retrogradely via the superior vena cava at a flow of 300 to 500 ml/min (n = 5). The brains were then fixed for quantitative measurement of the density of ink-filled capillaries (reported as a percentage of the total selected area). The assessment was done with the use of an in-house software program. RESULTS: In the antegrade cerebral perfusion group, the intracranial arterial and venous systems were completely filled with ink. The gray matter was colored uniformly black, and light coloring was observed in the white matter. During retrograde cerebral perfusion, the majority of ink was returned to the inferior vena cava, and only a small amount of ink was found in the innominate artery draining from the brain. Massive ink filling was observed in the sagittal sinus and other venous sinuses in all the pigs. Vessels on the surface of the brain and large vessels in the brain were also well filled with ink. However, only 10% of capillaries were filled with ink during retrograde cerebral perfusion relative to the number observed with antegrade cerebral perfusion. CONCLUSIONS: Retrograde cerebral perfusion supplies a limited amount of blood to brain tissue, which flows mainly through superficial and large deep cerebral vessels.

Animals↗

PubMed1997

Aspartate/glutamate-enriched blood does not improve myocardial energy metabolism during ischemia-reperfusion: a 31P magnetic resonance spectroscopic study in isolated pig hearts.

OBJECTIVE: Our objective was to test the effects of exogenous L-aspartate and L-glutamate on myocardial energy metabolism during ischemia-reperfusion. METHODS: Phosphorus 31-magnetic resonance spectroscopy was used to observe cellular energetics and intracellular pH in isolated pig hearts perfused with blood (group A, n = 8) or blood enriched with 13 mmol/L each of L-aspartate and L-glutamate (group B, n = 6). The hearts were subjected to 30 minutes of total normothermic ischemia and then reperfused for 40 minutes. Two hearts from each group were inotropically stimulated by titration with calcium after normokalemic reperfusion. Left ventricular function was measured with the use of a compliant balloon and oxygen consumption was calculated. RESULTS: Magnetic resonance spectroscopy showed no decrease in the rate of energy decline during ischemia for group B versus group A. No significant differences were observed between the two groups in terms of myocardial function, oxygen consumption, or the rate or extent of high-energy phosphate recovery after normokalemic reperfusion or inotropic stimulation. Inotropic stimulation of postischemic hearts, however, led to dramatic improvement in myocardial function in both groups (p < 0.05 for all parameters) and significant improvement in oxygen consumption (p = 0.01). CONCLUSIONS: In a normal, isolated, blood-perfused pig heart subjected to 30 minutes of total normothermic ischemia, (1) enrichment of the perfusate with aspartate/glutamate before and after ischemia affects neither myocardial energy metabolism during ischemia-reperfusion nor postischemic recovery of myocardial function or oxygen consumption and (2) inotropic stimulation can recruit significant postischemic function and sufficient aerobic respiration to support it, irrespective of aspartate/glutamate enrichment.

Adenosine Triphosphate↗

PubMed1997

Potential for non-shivering thermogenesis in perfused chicken (Gallus domesticus) muscle.

The humoral modulation of resting muscle heat production of chickens (Gallus domesticus) was investigated in vitro. The resting distal lower limb was perfused via the popliteal artery at 25 degrees C without erythrocytes at constant flow. The preparation was stable for at least 3 hr, showing a constant oxygen uptake (MO2) and perfusion pressure as well as adequately maintaining muscle energy charge and creatine phosphate: creatine ratio. Noradrenaline (NOR), adrenaline (ADR) and serotonin (5-HT) each caused a dose-dependent rise in perfusion pressure. NOR and ADR evoked increased MO2 at low doses eventually followed by decreased MO2 at higher agonist concentrations. 5-HT gave smaller but qualitatively similar MO2 effects. The actions of 50 nM NOR were blocked by prazosin (10 microM) and nitroprusside (0.5 mM), but not altered by propranolol (10 microM). NOR-induced stimulatory MO2 changes in the presence of pharmacological concentrations (1 microM) of glucagon were more pronounced and the thermogenic concentration range of NOR was increased. Taken together, these in vitro findings demonstrate a potential for vasoconstrictor-controlled muscle nonshivering thermogenesis in birds as in marsupials and mammals, suggesting that vascular control of muscle MO2 may be a widespread biological mechanism. The possible implications of these findings for avian nonshivering thermogenesis are discussed.

Animals↗

PubMed1997

Complementation cloning of S2P, a gene encoding a putative metalloprotease required for intramembrane cleavage of SREBPs.

We report the cloning of a gene, S2P, that encodes a putative metalloprotease required for intramembrane proteolysis of sterol-regulatory element-binding proteins (SREBPs) at Site-2. SREBPs are membrane-bound transcription factors that activate genes regulating cholesterol metabolism. The active NH2-terminal domains of SREBPs are released from membranes by sequential cleavage at two sites: Site-1, within the lumen of the endoplasmic reticulum; and Site-2, within a transmembrane segment. The human S2P gene was cloned by complementation of mutant CHO cells that cannot cleave SREBPs at Site-2 and are cholesterol auxotrophs. S2P defines a new family of polytopic membrane proteins that contain an HEXXH sequence characteristic of zinc metalloproteases. Mutation of the putative zinc-binding residues abolishes S2P activity. S2P encodes an unusual metalloprotease that cleaves proteins within transmembrane segments.

Animals↗

PubMed1997

Validation of the central-ray approximation for attenuated depth-dependent convolution in quantitative SPECT reconstruction.

In order to model photon attenuation and detector resolution variation as a depth-dependent convolution for efficient reconstruction of quantitative SPECT, a central-ray approximation is necessary. This work investigates the impact of the approximation upon reconstruction accuracy and computational efficiency. A patient chest CT image was acquired and converted into an object-specific attenuation map. From a segmentation of the map, an emission thorax phantom was constructed with a cardiac insert. To generate a system-specific resolution-variant kernal, a point source was measured at several depths from the surface of a low-energy, high-resolution, parallel-hole collimator of a SPECT system. Projections of parallel-beam geometry were simulated from the phantom, the map, and the kernel on an elliptical orbit. Reconstruction was performed by the ML-EM algorithm with and without the central-ray approximation. The approximation cuts down dramatically (more than 100 fold) the computing time with a negligible loss (less than 1%) of reconstruction accuracy.

Algorithms↗