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Biomedical subjects

Y Cai

Publications and source records attributed to Y Cai.

At least 235 records · Page 13Linked to original sources
PubMed1996

[Combination treatment of late nasopharyngeal carcinoma: an analysis of short-term therapeutic results in 200 cases].

Patients with late nasopharyngeal carcinoma (NPC) were divided into 4 groups, 50 each, treated with different protocols. Group A: radiotherapy plus systemic interlenkin 2 (IL-2), Group B: chemotherapy plus radiotherapy, Group C: chemotherapy plus radiation and IL-2, Group D: radiotherapy alone. Changes in the primary tumor and neck lymph nodes were monitored at 0, 3 and 6 months after treatment. In group A, the primary tumor regression rates (TRR) were 88%, 90% and 92%, and the lymph nodes regression rates (LNR) were 82%, 86% and 88%, respectively. In group B, the TRR were 86%, 88% and 90%, and the LNR were 80%, 84% and 86%, respectively. In group C, the TRR were 88%, 90% and 92%, and the LNR were 82%, 86% and 88%, respectively. In group D, the TRR were 78% 80% and 82%, and the LNR were 76%, 78% and 80%, respectively. The 1-year survival rates in these 4 groups of patients were 92%, 90%, 94% and 82%, respectively. Thus, the therapeutic results are significantly better in the combination treatment groups than those in the group receiving radiotherapy alone. In addition, IL-2 was effective to significantly reduce the occurrence of systemic side effects of radiotherapy and radiotherapy plus chemotherapy.

Adult↗
PubMed1996

Relaxant effects of vasoactive intestinal peptide on pulmonary artery in chronically hypoxic rats.

The object of this study is to investigate the effect of VIP on pulmonary artery of chronically hypoxic rats. It was shown that chronic hypoxia depressed significantly pulmonary artery relaxation induced by VIP as compared with those of control (P < 0.001). The vascular relaxation of both groups was correlated with concentration of VIP. In addition, the relaxant effect of VIP on pulmonary arteries in rats was endothelium-independent, and was not prevented by indomethacin or nordihydroguaiaretic acid, but was abolished completely by methylene blue. These results suggest that the lower relaxation of pulmonary artery in rats might not be due to the endothelial injury caused by chronic hypoxia, and chronic hypoxia may inhibit directly the soluble guanylate cyclase in vascular smooth muscle cells involved in synthesis of cGMP and thus reduced the sensitivity and reactivity of pulmonary artery to VIP.

Animals↗
PubMed1996

Hypoxia and endothelin-1 stimulate DNA synthesis of pulmonary artery smooth muscle cells.

Hypoxia and endothelin-1 (ET-1) are associated with constriction of pulmonary vasculature both in vivo and in vitro. However, the role of hypoxia and ET-1 in the vascular remodelling during the development of pulmonary hypertension is unclear. This study demonstrated that ET-1 (0.1 nmol/L to 100 nmol/L) increased the [3H] thymidine uptake in a dose-dependent manner in cultured bovine pulmonary artery smooth muscle cells (PASMC), which was enhanced by exposing PASMC to hypoxia (2% O2, 93% N2, 5% CO2). BQ123, the specific antagonist of endothelin receptor subtype A, eliminated the ET-1 medicated proliferation of PASMC and the cooperative effect of hypoxia. Some dilatory drugs could inhibit the mitogenic effect of ET-1. We also observed that hypoxia significantly increased [3H]thymidine uptake in PASMC without ET-1 and BQ123 could inhibit this effect. Radioimmunoassay suggested that there was an autocrine of ET-1 in cultured PASMC which was enhanced by hypoxia significantly.

Animals↗
PubMed1996

MR evaluation of the brain in central diabetes insipidus.

OBJECTIVE: To evaluate the role of magnetic resonance (MR) imaging in determining the cause of central diabetes insipidus (CDI) by using MR imaging to describe the findings in the hypothalamic-pituitary area in patients with CDI. METHODS: Thirty-one cases of clinically proved CDI were prospectively studied. A control study was also conducted in 200 normal subjects. MR imaging was performed on a 1.0 T superconductive unit with T1-weighted images obtained in the sagittal, coronal and axial planes. RESULTS: Hypothalamic-pituitary masses or structural changes were identified in 26 cases and normal structures in 5. The normal high signal intensity of the posterior pituitary lobe was absent in 29 cases, but remained unchanged in 2. In the control group, the frequency of the high signal of the posterior lobe was 93%. CONCLUSIONS: The absence of the normal high signal in the posterior pituitary lobe is closely related to the loss of hypothalamic-pituitary function. MR imaging is very sensitive in demonstrating the changes in this area in CDI and it can provide an accurate diagnosis when combined with the clinical information.

Adolescent↗
PubMed1996

[Obesity-hypoventilation syndrome].

5 cases with obesity-hypoventilaion syndrome were reported. The clinical manifestations were obesity, palpitation, dyspnea, lethargy, cyanosis, distention of cervical vein, edema, enlargement of liver and hypertension. All of them were initially diagnosed as chronic bronchitis or heart diseases. Pulmonary function test showed restrictive ventilative defect and hypercapnia with hypoxemia. Mouth oclusion pressure at 0.1 second was higher than the normal value. The response to CO2 was decreased. Hypertrophy of right heart was shown in ECG and X-ray film improvement in symptoms and blood gases analyses were found to be associated with body weight decrease in a follow up period of one year.

Adult↗
PubMed1996

Effect of hypoxia on DNA synthesis and c-myc gene expression of pulmonary artery smooth muscle cells.

The neonate is particularly susceptible to the development of hypoxic pulmonary hypertension. The present study was undertaken to observe the effect of hypoxia on DNA synthesis and c-myc gene expression between newborn calf and adult bovine PASMC in vitro. DNA synthesis measured by 3H-TdR incorporation was increased after hypoxic challenge for 24h. Hypoxia enhanced the increment in 3H-TdR incorporation induced by EGF. Northern blot analysis revealed that PASMC cultured in both normoxia and hypoxia expressed c-myc gene transcript of 2.2Kb, but there is a higher 2. 2Kb mRNA expression in hypoxic PASMC than that in normoxia. We speculate that newborn calf PASMC exhibited potential response to hypoxia than adult, which was augmented by EGF. Enhanced c-myc gene expression may lead to a great understanding of the mechanism of PASMC growth in the development of pulmonary hypertension.

Animals↗
PubMed1996

Increased expression of PDGF and c-myc genes in lungs and pulmonary arteries of pulmonary hypertensive rats induced by hypoxia.

The role of growth factors and proto-oncogene in pulmonary vascular structural remodelling is not well known. The present study examined gene expression of platelet-derived growth factor (PDGF)-A and -B chain and proto-oncogene, c-myc, in lung tissue and pulmonary artery of rats exposed to hypoxia and compared to those levels of gene expression in normal rats. Normal lungs and pulmonary artery expressed PDGF-A chain transcript of 1.7 kb and PDGF-B chain transcript of 3.5 Kb. The c-myc transcript of 2.2 kb was expressed as well. After hypoxic exposure for 7 and 14 days mRNA levels of PDGF-B chain and c-myc were elevated significantly compared with those of control rats. PDGF-A chain mRNA increased after hypoxia for 7 days, and then declined. These results suggest that activation of autocrine and/or paracrine is important in proliferation mechanism of pulmonary artery smooth muscle cells in hypoxic pulmonary hypertensive rats.

Animals↗
PubMed1996

[Endothelin-1 induces chemotaxis of pulmonary artery smooth muscle cells].

Migration of pulmonary artery smooth muscle cells (PASMC) and their precorsors might be an important mechanism of pulmonary vascular structural remodelling associated with hypoxic pulmonary hypertension (HPH). Endothelin-1 (ET-1) plays an important role in the pathogenesis of HPH. This study observed that ET-1 induced chemotaxis of PASMC in a dose dependent manner. The maxium chemotactic response of PASMC to ET-1 occured at a concentration of 10(-9) mol/L. The chemotactic activity of ET-1 is weakened, when its concentration is higher than 10(-9) mol/L. BQ123, a specific antagonist of ETRA, significantly inhibited the chemotaxis of PASMC induced by ET-1, which indicates that the chemotactic activity of ET-1 may be mediated by ETRA. Hypoxia enhanced the chemotaxis of PASMC induced by ET-1. This study suggests that ET-1 and hypoxia might stimulate the migration of PASMC and/or its precorsor. The further mechanism is under study.

Animals↗
PubMed1996

[Observation on therapeutic effect of megestrol acetate on patients with chronic obstructive pulmonary disease at remission stage].

It has been reported that malnutrition is common in stable chronic obstructive pulmonary disease (COPD) patients. In order to observe the effects of Megestrol Acetate (MA) on nutritional status, respiratory muscle strength and immunological parameters in stable COPD patients, 31 stable COPD patients were divided into two groups at random--a treatment group of 16 cases and a control group of 15 cases. Before and after treatment all parameters were recorded, including food and energy intake, body weight, triceps skinfolds (TSF), pre-albumin, transferrin, albumin. Lung function, respiratory muscle and handgrip strength were examined and immunological parameters also determined. After taking MA 160 mg/day orally for two weeks, the treatment group got benefits as follows: heat energy and protein intake increased fro 6977.9 +/- 1136 kJ/d and 44.65 +/- 13.75 g/d to 9854.0 +/- 2355.3 kJ/d and 84.80 +/- 20.23 g/d respectively. With the increase of daily energy and protein intake, body weight increased from 48.27 +/- 8.61kg to 50.34 +/- 8.76 kg, TSF from 11.75 +/- 4.50 mm to 15.06 +/- 4.73 mm, serum pre-albumin from 306.6 +/- 33.7 mg/L to 332.6 +/- 1 mg/L, transferrin from 3.09 +/- 0.21 g/L to 3.46 +/- 0.32 g/L, albumin from 38.00 +/- 1.73 g/L to 42.64 +/- 3.36 g/L, MIP from 4.77 +/- 2.14 kPa (1 kPa = 7.5 mmHg) to 6.31 +/- 2.87 kPa, MEP from 6.21 +/- 2.90 kPa to 7.20 +/- 3.67 kPa and 6 minutes walking distance from 280.2 +/- 76.4 m to 370.6 +/- 81.5 m. Handgrip strength also improved. Blood lymphocyte transformation rate elevated too. (The changes of all these parameters indicated above were statistically significant, P < 0.01). However, parameters of lung function, blood gas analysis, serum immunoglobulin and complement 3 did not change significantly. In 15 control patients all the parameters did not change significantly. There were few side effects; only one case complained of nausea and vomiting. It was shown that MA can stimulate appetite and increase dietintake, improve nutritional status, elevate respiratory muscle strength, and enhance immunity. MA is a safe and effective drug which exerts a beneficial influence on stable COPD.

Aged↗
PubMed1995

Effects of arginine vasopressin and angiotensin II on area postrema neurons in rabbit brain slice preparation.

Previous in vivo studies have indicated that both arginine vasopressin (AVP) and angiotensin II (ANG II) can modulate the baroreflex by acting on the area postrema (AP). In the present study, effects of AVP and ANG II on AP neuronal activity were investigated by recording extracellular activity in a rabbit brainstem slice preparation. AVP (1 nM-1 microM) inhibited 14.5% and excited 53.2% of the neurons while ANG II (1 nM-5 microM) inhibited 32.3% and excited 29% of the neurons. Application of AVP and ANG II to the same AP neurons at the same concentration indicated that more AP neurons responded to AVP than to ANG II. ANG II induced more inhibitory responses than AVP. The results suggest that AVP and ANG II may produce different effects on the baroreflex by acting on different pools of AP neurons and by exerting different effects on the same AP neuron.

Action Potentials↗
PubMed1995

Deregulation of c-abl mediated cell growth after retroviral transfer and expression of antisense sequences.

To determine the role of c-abl during cell growth, we constructed a retrovirus vector alpha A, capable of expressing an antisense RNA directed against the abl mRNA. Based on v-abl-mediated 3T3 transformation assay, we showed that the number of transformed foci was reduced 50-94% when alpha A-infected 3T3 cells were superinfected with A-MuLV. Up to a 100% of inhibition could be observed when the time of infection was lengthened. Introduction of the antisense sequence into NIH3T3 cells resulted in reduction of growth rate. These cells entered into S phase from G1 phase of the cell cycle earlier in time than untransduced cells. Thus c-abl serves as a checkpoint during G1/S transition in the cell cycle, and its reduction resulted in deregulation of cell growth.

3T3 Cells↗
PubMed1995

Enhanced expression of catalytic subunit isoform PP1 gamma 1 of protein phosphatase type 1 associated with malignancy of osteogenic tumor.

The expressions of the three catalytic subunits of protein phosphatase (PP) type 1 and 2A, PP1 alpha, PP1 gamma 1, and PP2AC, were examined in 14 cases of three types of osteogenic tumor using immunohistochemical analysis. The percentage of tumor cells stained positively with antiserum against PP1 catalytic subunit-isoform PP1 gamma 1 was significantly higher in malignant osteogenic tumors than in benign osteogenic tumors. Furthermore, malignant osteogenic tumor showed markedly high S-phase fraction in the cell cycle of tumor cells, as compared to benign osteogenic tumors. These results suggest that PP1 gamma 1 is involved in the accelerated growth of malignant cells in osteogenic tumors.

Adolescent↗
PubMed1995

Hepatic oxidative stress and related defenses during treatment of mice with acetylsalicylic acid and other peroxisome proliferators.

The peroxisome proliferators perfluorooctanoic acid (PFOA; 0.02% w/w), perfluorodecanoic acid (PFDA; 0.02%, w/w), nafenopin (0.125%, w/w), clofibrate (0.5%, w/w), and acetylsalicylic acid (ASA; 1%, w/w) were administered to male C57 BL/6 mice in their diet for two weeks. Parameters for Fe3+ ADP, NADPH or ascorbic acid-initiated lipid peroxidation in vitro were measured. Approximately a twofold increase in susceptibility to lipid peroxidation was obtained for all the peroxisome proliferators tested. Cotreatment of mice with the peroxisome proliferator ASA (1%, w/w) and a catalase inhibitor, 3-amino-1,2,4-triazole (AT; 0.4%, w/w) for 7 days resulted in little inhibition of peroxisome proliferation, an elevated level of H2O2 in vivo, and total inhibition of the increased susceptibility to lipid peroxidation in vitro. No increase in lipid peroxidation in vivo was observed. Certain antioxidant enzymes (DT-diaphorase, superoxide dismutase, glutathione transferase, glutathione peroxidase, and glutathione reductase) and components (ubiquinone and alpha-tocopherol) were also measured. The results showed that there was some induction of these antioxidant enzymes and components by ASA or aminotriazole, except for glutathione peroxidase and superoxide dismutase, which were inhibited. The possible involvement of oxidative stress in the carcinogenicity of peroxisome proliferators is discussed.

Acyl Coenzyme A↗
PubMed1995

A mutant strain (LEC) of rat with low degree of zinc-induced hepatic metallothionein gene expression.

A mutant strain (LEC) of rats was found to possess the feature of low degree of the zinc-induced hepatic metallothionein (MT) gene expression due to an alteration of the transcription factor concerned in the gene expression. Northern blot analyses showed that the amount of MT-1 mRNA induced by intraperitoneal zinc injection is smaller in LEC mutant rat liver than in normal rat liver, while the amount of MT-1 mRNA induced by copper injection is indistinguishable between LEC and normal rat livers. Gel retardation assays showed that LEC and normal rat livers are different in the nuclear protein which binds to the metal-responsive element (MRE) of the MT gene in a zinc-dependent manner, and that the efficiency of the zinc-dependent binding of the nuclear protein to the MRE is lower in LEC rat liver than in normal rat liver. LEC rat should provide a useful model to understand the transcription factor concerned in the MT gene expression by zinc.

Animals↗
PubMed1995

Allyl alcohol cytotoxicity in isolated rat hepatocytes: effects of azide, fasting, and fructose.

The role of altered energy homeostasis in the lethality of allyl alcohol to isolated rat hepatocytes was studied. ATP, ADP, AMP, and viability loss (leakage of lactate dehydrogenase into the medium) were measured in isolated hepatocytes of fed or fasted rats exposed to 0.5 mM allyl alcohol. Adenine mononucleotides and cytotoxicity were determined also in hepatocytes incubated with allyl alcohol in the presence of 4 mM sodium azide or 15 mM fructose. Allyl alcohol-induced cell death in hepatocytes of fed rats was preceded by slight decreases in ATP content and energy charge (16% and 12%, respectively). More substantial decreases in these parameters occurred in parallel with cell killing, but the effect of allyl alcohol on energy status did not exceed the effect produced by a nonlethal concentration of sodium azide. Neither azide nor fructose affected the development of allyl alcohol cytotoxicity. Moreover, allyl alcohol-induced cytotoxicity was similar in hepatocytes of fed and fasted rats. The results suggest that altered energy homeostasis is a consequence rather than a cause of allyl alcohol-induced hepatocyte lethality.

1-Propanol↗