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Biomedical subjects

Y Yu

Publications and source records attributed to Y Yu.

At least 397 records · Page 22Linked to original sources
PubMed1997

Cell-type specific calcium signalling in a Drosophila epithelium.

Calcium is a ubiquitous second messenger that plays a critical role in both excitable and non-excitable cells. Calcium mobilisation in identified cell types within an intact renal epithelium, the Drosophila melanogaster Malpighian tubule, was studied by GAL4-directed expression of an aequorin transgene. CAP2b, a cardioactive neuropeptide that stimulates fluid secretion by a mechanism involving nitric oxide, causes a rapid, dose-dependent rise in cytosolic calcium in only a single, genetically-defined, set of 77 principal cells in the main (secretory) segment of the tubule. In the absence of external calcium, the CAP2b-induced calcium response is abolished. In Ca2+-free medium, the endoplasmic reticulum Ca2+-ATPase inhibitor, thapsigargin, elevates [Ca2+]i only in the smaller stellate cells, suggesting that principal cells do not contain a thapsigargin-sensitive intracellular pool. Assays for epithelial function confirm that calcium entry is essential for CAP2b to induce a physiological response in the whole organ. Furthermore, the data suggest a role for calcium signalling in the modulation of the nitric oxide signalling pathway in this epithelium. The GAL4-targeting system allows general application to studies of cell-signalling and pharmacology that does not rely on invasive or cytotoxic techniques.

Adenosine Triphosphatases↗
PubMed1997

Enhancement of splenic interferon-gamma, interleukin-2, and NK cytotoxicity by S36 acupoint acupuncture in F344 rats.

The effect of Tsusanli acupuncture point (S36 acupoint) stimulation on splenic natural killer (NK) cytotoxicity was examined in Fischer 344 (F344) rats. Electro-acupuncture stimulation (voltage intensity, 1 to 5 V; duration, 1 ms; frequency, 1 Hz) was applied to bilateral S36 acupoints once a day (1 h) for 3 d. NK cytotoxicity was measured by the standard 4-h 51Cr release assay. Successive acupuncture treatment for 3 d significantly enhanced splenic NK cytotoxicity (p < 0.001) on the first day after final treatment as compared to that of the control. However, similar stimulation to abdominal muscle did not influence splenic NK cytotoxicity. We also examined endogenous cytokine activities in aqueous spleen extracts prepared from acupunctured and control rats. The extracts from rats acupunctured at the S36 acupoint contained high levels of interleukin (IL)-2 and interferon (IFN)-gamma as compared to those of abdominal muscle acupunctured and non-acupunctured control rats (p < 0.01). Furthermore, a significant positive correlation (p < 0.01) was observed between the levels of each cytokine tested and splenic NK cytotoxicity. The same positive correlation was also observed between the levels of IL-2 and IFN-gamma (p < 0.01). These observations indicate that electro-acupuncture stimulation of the S36 acupoint enhances splenic NK cytotoxicity and that IL-2 and IFN-gamma may function, at least in part, in the regulation of NK cell activity in this system.

Abdominal Muscles↗
PubMed1997

Induction of apoptosis in human leukemic cells by magnetic fields.

When human myelogenous leukemic cell lines, HL-60 and ML-1, were exposed to 50 Hz electromagnetic fields (EMFs), nucleosome-sized DNA fragmentation (a biochemical marker of apoptosis) was induced as assessed by agarose gel electrophoresis. However, EMFs could not induce detectable DNA fragmentation in either human peripheral blood leukocytes or polymorphonuclear cells. The minimum exposure period required for the onset of DNA fragmentation in leukemic cells was 1.0 h. Although adverse effects of EMFs on human health have been reported, the apoptosis-inducing action of EMFs on leukemic cells may suggest a possible medical application.

Apoptosis↗
PubMed1997

[The relationship between abnormalities of cell-mediated immunity and gut origin endotoxemia in a rat model of thermal injury].

This study was conducted to determine the relationship between abnormalities of cell-mediated immunity and gut-derived endotoxemia in rats following burns. Animals were subjected to a 40% full-thickness scald injury, and randomly divided into control and selective decontamination of the digestive tract (SDD) treated groups. It was found that thermal injury resulted in marked reductions in splenocyte proliferative response to concanavalin A or phytohemagglutinin, interleukin 2 (IL-2) production, and T helper/suppressor (Th/Ts) cells ratio. Prophylactic treatment with SDD significantly reduced the incidence of endotoxemia, prevented suppressive mitogenic response and inadequacy in IL-2 production (P < 0.05-0.01), but did not affect the abnormal ratio of Th/Ts in blood (P > 0.05). We conclude that bacteria/endotoxin translocation from the gastrointestinal tract appears to be involved in cellular immune dysfunction after thermal injury. Pretreatment with SDD might attenuate systemic immunosuppression by preventing translocation events.

Animals↗
PubMed1997

[Serum neopterin levels after extensive burns and their relationship to endotoxemia and sepsis].

The present study was performed to determine the kinetics of serum neopterin levels after major thermal injury and their relationship to endotoxemia and sepsis. This prospective study included 35 patients (32 males and three females) with total burn surface area (TBSA) greater than 30% (30%-98%), and 22 healthy volunteers who served as normal controls. The results showed that neopterin levels increased in most patients on day 3 postburn, but they were not significantly correlated with the extent of the burn surface (P > 0.05). Patients with endotoxemia had much higher neopterin values than those who showed no endotoxemia from the second week onward (P < 0.05-0.01), and circulating endotoxin and neopterin levels were positively correlated in patients who developed endotoxemia on day 14 (r = 0.368, P < 0.05) and day 21 (r = 0.439, P < 0.01) after major burns. Moreover, a high serum neopterin level was found in patients with sepsis (n = 15), and the marked elevation persisted throughout the observation period. The difference between septic and non-septic patients (n = 20) became significant on 14 and 28 days postburn. These data suggest that extensive burns can lead to an elevation of serum neopterin independent of TBSA. The endotoxin release in the circulation may be involved in the continuous formation of neopterin during the late postburn stage. In addition, the presence of a constant high neopterin level is associated with a critical event in the development of burn sepsis.

Adolescent↗
PubMed1997

[Surgical consideration in congenital partial atrioventricular septal defect in 59 patients].

We report surgical anatomic characteristics, timing of surgery, corrective methods of partial atrioventricular defect and prevention of complications. In the past 15 years, we operated on 59 patients with partial atrioventricular septal defect, associated with conduction abnormality in 39 patients, common atrium in 2, mitral insufficiency (MI) in 54, tricuspid insiufficiency in 29, andunroofed coronary sinus in 6. One patient could not wean from cardiopulmanary bypass and died during operation. After surgery, 5 patients had moderate residual MI, and 1 complete heart block. During 1 to 16 years of followup, all but 1 patient with class III (NYHA) had satisfactory results.

Adolescent↗
PubMed1997

[Liver resection after transcatheter hepatic arterial chemoembolization for hepatocellular carcinoma and curative effect analysis].

To study the therapeutic result of hepatic resection for those hepatocellular carcinoma (HCC) shrunked after transcatheter hepatic arterial chemoembolization (TACE) in the patients with unresectable HCC, authors reported 59 patients with HCC. Among the 59 patients, the maximum diameter of the tumor was 5.6 to 20.0 cm prior to the first TACE, mean 9.43 cm. The patients underwent 1 to 6 times of TACE, mean 2.9 times. The tumor diameters were reduced to 3.29 cm prior to operations. The duration between the last TACE treatment and sequential resection varied from 1 to 7 months, mean 2.53 months. Of the 59 patients, 35 patients' serum alpha-fetoprotein (AFP) levels were elevated. AFP levels returned to normal after TACE treatment in 13 patients. Of the patients, liver segmentectomy, combined liver segmentectomy or partial liver resection was performed in 56 patients, left trilobectomy in 2 and left hemihepatectomy in 1. Tumor necrosis ranged from 40% to 100% pathologically and complete tumor necrosis occurred in 9 patients. Of the 13 patients with AFP levels decreased to normal, 9 still had microscopic living tumor foci. The 1-, 3- and 5- year survival rates were 79.7%, 65% and 56%, respectively. These results indicated that TACE treatment can provide chance of tumor resection for those patients with unresectable HCC and good results can be obtained.

Adult↗
PubMed1997

[Auxiliary partial orthotopic liver transplantation in rats].

A rat model of auxiliary partial orthotopic liver transplantation (APOLT) was developed in this study. Under hemihepatic inflow and outflow occlusions, the recipient underwent 75% partial hepatectomy before the liver graft comprising 30% of the donor liver was implanted on the orthotopic site. Forty rat APOLT were successfully performed. The 5-day survival rate of the recipient was 87.5% and that of the graft was 75%. On the fifth postoperative day, the living graft weight increased by 100%, the liver cell showed an active proliferation with a diploid of deoxyribonuclease (DNA), and the liver cells in DNA-synthetic phase accounted for 22.6 +/- 2.75%, significantly exceeding 12.22% +/- 1.48% of the normal rat hepatocytes (P < 0.001). It may be concluded that the rat APOLT is a more ideal animal model.

Animals↗
PubMed1997

[Clinical application of transmyocardial laser revascularization].

Transmyocardial laser revascularization (TMLR), a new technique, provides direct perfusion of ischemic myocardium via laser-created transmural channels. From 1995 to 1996, we treated 7 patients (mean age 60 years, all men) with TMLR. Preperatively, 5 patients were in angina class (C. C. S) 3-4 and 2 patients had unstable angina. To identify the location and extent of their reversible ischemia, the coronary angiogram, 99mSPECT and/or dobutamine echocardiography was performed before operation in 7 patients. Through a left anterior thoractomy in the fifth intehcostal space, heart exposure was gained. With the use of a 700-watt CO2 laser, TMLR was performed on the beating heart. An average of 22 +/- 3 channels were created in 45 minutes with a total operative time of less than 2 and half hours. The in hospital mortality was one of 7 patients. Follow-up ranged from 2 to 12 months (accumulated 48 patient-months). Postoperatively, the relief of angina was noted in 6 patients. Postoperative SPECT and dubatamin-UCG were obtained at 3, 6, and 12 months. (99mTc) SPECT showed a significant improvement of myocardial perfusion in the area of reversible ischemia. Dobutamin-UCG documented an increase in the ventricular wall motion and LVEF in 2 patients as compared with basline. These early results indicate that TMLR may provide angina relief, improve myocardial perfusion and increase cardiac function for patients with ischemic heart disease.

Aged↗
PubMed1997

[The study on insulin secretion function of beta-cell in new diagnosed type II diabetic patients].

To determine type II diabetes in association with alteration in beta-cell function, we studied 30 patients with newly diagnosed diabetes and 30 matched controls. The beta-cell 1st phase insulin response was measured by intravenous glucose tolerance test and the 2nd phase insulin response was measured by oral glucose tolerance test. The results revealed that in type II diabetes mellitus the pulse of 1st phase insulin secretion could not be found. The amount of 2nd phase insulin secretion of the patients was lower than that normal controls, and the patients' secretary pulse of insulin was not concomitant with glucose pulse. These findings again suggest it is the defect in beta-cell function, not the peripheral resistance an essential cause of overt type II diabetes.

Diabetes Mellitus, Type 2↗
PubMed1997

Study on small hepatocellular carcinoma and its extension.

This paper summarizes the "study on small hepatocellular carcinoma and its extension" in Liver Cancer Institute, Zhongshan Hospital of Shanghai Medical University during the past 25 years. The results indicated that it was an important approach to obtain long-term HCC survivors, of the 239 patients with 5-year survival, small HCC resection accounted for 51.4%. It was an effective approach to improve the prognosis of HCC in the entire series, the 5-year survival of inpatients treated in authors' institution was 4.8% in 1958-1970, 12.2% in 1971-1983, and 46.7% in 1984-1995; which were correlated to the increase proportion of small HCC resection in the series; it was more effective as compared to large HCC resection, the 5 year survival was 61.3% (n = 645) versus 33.6% (n = 950). Extensions of small HCC study included early detection and treatment of small recurrent HCC, of the 147 patients with re-resection, the 5-year survival was 48.9% calculated from the time of first resection. Another extension was conversion of large HCC into small HCC, using multimodality combination treatment, 72 out of the 663 patients with surgically verified unresectable HCCs have been converted to resectable, 5-year survival being 62.1%, which was comparable to that of small HCC resection. Studies on related basic aspect of small HCC such as cell origin of recurrence, and molecular aspect of small HCC, indicated that biological characteristics, particularly the tumor invasiveness, remained the key link for further prolong survival after small HCC resection. Recently, a "patient-like" human HCC metastatic model in nude mice has been established. Experimental interventions have also been tried. Clinical trials for prevention of recurrence after small HCC resection have shown preliminary encouraging results. However, the "cost-effectiveness" of screening, the invasiveness of HCC, the multicentric origin, the coexisted Child C cirrhosis, etc., remained great challenge.

Animals↗
PubMed1997

Stable expression of human cytochrome CYP2B6 and CYP1A1 in Chinese hamster CHL cells: their use in micronucleus assays.

With specific designed primers, CYP2B6 and CYP1A1 cDNA were generated by reverse transcription-polymerase chain reaction(RT-PCR) technique performed on total RNAs isolated from human liver and 3-methylcholanthrene(3-MC) induced human amnion FL cells. Cell lines (CHL-2B6 and CHL-1A1) capable of expressing human cytochrome P450(CYP)2B6 and 1A1 were established after transfection of corresponding eukaryotic recombinant expression plasmid with human CYP2B6 and 1A1 cDNA inserts respectively. These cell lines stably expressed the mRNAs and the enzymatic activities corresponding to CYP2B6 and CYP1A1, respectively. Compared with Chinese hamster 1ung(CHL) cells, the micronucleus frequency in CHL-2B6 cells is markedly increased when exposed to nitrosamines, aflatoxin B1(AFB1) and cyclophosphamide (CPA). This is also in CHL-1A1 cells, when exposed to carcinogenic polycyclic aromatic hydrocarbons.

Animals↗
PubMed1997

[A study of using wavelet transform in the filtering method for ECG signal].

In this paper a filtering method for ECG signal is introduced which decomposes original ECG signals into detail signals on different frequency bands by using Wavelet Transform(WT). According to ECG signal feature, some detail signals are discarded, and the retained signals are reconstructed by inverse WT, so three main interferences in ECG signal can be removed. Our experimental results demonstrate that this is an efficient filtering method.

Algorithms↗
PubMed1997

[Observation on acupoint electric potential in pilots under vestibular stimulation].

To study the possibility of using acupoint electric potential as an index for evaluation of pilot's reaction to vestibular stimulation, electric potential was measured on both sides of left and right Neiguan points and Zusanli points in 80 pilots. Rotation chair was used as the method of stimulation. The results showed that changes of acupoint electric potentials were not significant (P >0.05) during 5 min uniform rotation. While the changes under head motion stimulation were significant (P<0.05 or 0.01) as compared with the pretest values. Relationship between symptoms and the corresponding acupoint potential changes remain to be studied further.

Acupuncture Points↗
PubMed1997

[Analysis of frequency domain correlative cardiogram (FCG) in 151 healthy pilots].

Frequency domain correlative cardiogram (FCG) is a relatively new noninvasive method for diagnosis of coronary heart disease. However there has been little information about the application of FCG in pilots. To explore whether the FCG diagostic standards of normal people, can be applied to healthy pilots, 151 male pilots aged 22-47 (mean = 30 +/- 6 years) were examined with the HBD-II A instrument manufactured by Hong Kong WEX company. The results showed that the characteristics of FCG graph of the pilots were similar to that of the common healthy men. It indicates that the diagnostic standard of FCG for normal people can be used to pilots, so it might be useful in selection and real-time medical monitoring during ground training.

Adult↗
PubMed1997

[Changes of electrogastrogram in pilots under vestibular stimulus].

The active electrogastrogram (EGG) of 81 pilots under vestibular stimulus was recorded and analysed by the method of running spectrum analysis. The subjects were randomly divided into group A and B. The results showed: that changes in dominant frequency instability coefficient (DFIC), dominant power instability coefficient(DPIC), tachygastria, bradygastria and normal slow wave components (NSW) of EGG occured under vestibular stimulus. These parameters of EGG may be used as indices to reflect the function of autonomic nervous system under vestibular stimulus. No difference of those parameters had been found between group A and B during the period of per-rotating, and the period of rotation.

Aerospace Medicine↗
PubMed1997

[EGG and nausea under vestibular stimulus].

81 pilots were exposed to vestibular stimulus with Coriolis acceleration. They were divided into two groups, the first group consisted of 38 pilots with nausea symptoms, the second group 43 pilots without nausea symptom. Dominant frequency instability coefficient (DFIC), dominant power instability coefficient (DPIC), Tachygastria, Bradygastria and normal slow wave components (NSW) of the electrogastrogram (EGG) were analyzed. The results showed that Bradygastria and NSW of EGG were related to nausea symptom of pilots under Coriolis stimulation.

Aerospace Medicine↗