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Biomedical subjects

P Zeng

Publications and source records attributed to P Zeng.

At least 19 recordsLinked to original sources
PubMed2003

A novel permanent maglev impeller TAH: most requirements on blood pumps have been satisfied.

Based on the development of an impeller total artificial heart (TAH) (1987) and a permanent maglev (magnetic levitation) impeller pump (2002), as well as a patented magnetic bearing and magnetic spring (1996), a novel permanent maglev impeller TAH has been developed. The device consists of a rotor and a stator. The rotor is driven radially. Two impellers with different dimensions are fixed at both the ends of the rotor. The levitation of the rotor is achieved by using two permanent magnetic bearings, which have double function: radial bearing and axial spring. As the rotor rotates at a periodic changing speed, two pumps deliver the pulsatile flow synchronously. The volume balance between the two pumps is realized due to self-modulation property of the impeller pumps, without need for detection and control. Because the hemo-dynamic force acting on the left impeller is larger than that on the right impeller, and this force during systole is larger than that during diastole, the rotor reciprocates axially once a cycle. This is beneficial to prevent the thrombosis in the pump. Furthermore, a small flow via the gap between stator and rotor from left pump into right pump comes to a full washout in the motor and the pumps. Therefore, it seems neither mechanical wear nor thrombosis could occur. The previously developed prototype impeller TAH had demonstrated that it could operate in animal experiments indefinitely, if the bearing would not fail to work. Expectantly, this novel permanent magnetic levitation impeller TAH with simplicity, implantability, pulsatility, compatibility and durability has satisfied the most requirements on blood pumps and will have more extensive applications in experiments and clinics.

Heart, Artificial↗
PubMed2002

Recent progress in developing durable and permanent impeller pump.

Since 1980s, the author's impeller pump has successively achieved the device implantability, blood compatibility and flow pulsatility. In order to realize a performance durability, the author has concentrated in past years on solving the bearing problems of the impeller pump. Recent progress has been obtained in developing durable and permanent impeller blood pumps. At first, a durable impeller pump with rolling bearing and purge system has been developed, in which the wear-less rollers made of super-high-molecular weight polythene make the pump to work for years without mechanical wear; and the purge system enables the bearing to work in saline and heparin, and no thrombus therefore could be formed. Secondly, a durable centrifugal pump with rolling bearing and axially reciprocating impeller has been developed, the axial reciprocation of rotating impeller makes the fresh blood in and out of the bearing and to wash the rollers once a circle; in such way, no thrombus could be formed and no fluid infusion is necessary, which may bring inconvenience and discomfort to the receptors. Finally, a permanent maglev impeller pump has been developed, its rotor is suspended and floating in the blood under the action of permanent magnetic force and nonmagnetic forces, without need for position measurement and feed-back control. In conclusion, an implantable, pulsatile, and blood compatible impeller pump with durability may have more extensive applications than ever before and could replace the donor heart for transplantation in the future.

Blood↗
PubMed2001

Peptides derived from pro-growth hormone-releasing hormone activate p38 mitogen-activated protein kinase in GH3 pituitary cells.

Posttranslational processing of the pro-growth hormone-releasing hormone (proGHRH) peptide can result in the formation of at least two peptide products: GHRH and the C-terminal peptide, GHRH-related peptide (GHRH-RP). While cyclic adenosine monophosphate transduces many of the actions of GHRH, other pathways also have been implicated in its actions. The aims of this study were to examine and characterize the activation of mitogen-activated protein kinase (MAPK) pathways by GHRH, and GHRH-RP in pituitary-derived GH3 cells, as well as the activation of the transcription factors that serve as substrates for these kinases. GHRH rapidly increased p44/p42 MAPK activity in GH3 cells in a protein kinase A-dependent and a protein kinase C-independent manner and stimulated the activation of the transcription factor Elk-1. By contrast, GHRH-RP and p75-92NH2 had no effect on p44/p42 MAPK phosphorylation in these cells. Additionally, we determined that all three peptides, GHRH, GHRH-RP, and p75-92NH2, rapidly and specifically increase phosphorylation of p38 MAPK and stimulate the activation of the nuclear factor CHOP. These are the first studies to demonstrate the activation of Elk-1 by GHRH and the activation of p38 MAPK and CHOP by GHRH, GHRH-RP, and p75-92NH2. We conclude that members of the GHRH family of peptides differentially activate multiple intracellular signaling pathways and suggest that the biologic actions of GHRH may be far more diverse than previously thought.

Animals↗
PubMed2001

[A permanent implantable pulsatile impeller heart with a specially devised needle bearing].

The author's implantable pulsatile impeller pump can assist the circulation of the calves for several months. The termination of the experiments was related to wear of the mechanical bearing, which resulted in vibration of the rotor and pump failure. It seemed as if the experiments could have lasted indefinitely if the bearing had not failed. To solve the problem of bearing wear, a specially devised rolling bearing was investigated and applied to the impeller pump. Its service life is more than 10 years due to the wear-proof roller made of ultra-highmolecular weight polythene. This newly devised impeller heart promises to have long-term and permanent applications. Compared with the magnetic bearing, the rolling bearing has the advantages of simpler construction and control, no consumption of energy, and better reliability.

Animals↗
PubMed2001

Membrane bioreactor process of organic wastewater from brassylic acid manufacturing plant.

The wastewater treatment from brassylic acid manufacturing plant using membrane bioreactor (MBR) was studied. The membrane bioreactor consisted of batch-operation biological aeration tank and ultrafiltration evaluation tank. The content of test included the affection of variation operation conditions on ultrafiltration separation, the general characteristics of MBR process, and the difference comparing with the conventional biological treatment. The results are as follows: (1) among the test membrane material, polyether sulphone (PES) membrane is more suitable for the wastewater treatment; (2) when the cutoff molecular weight is among 10,000-50,000, the higher the cutoff molecular weight, the bigger the water flux is in the test; (3) under the operation pressure, water flux increases accompanying with the increasing of operation pressure; (4) the paper filtered COD concentration has more affection on the water flux than the suspended solid concentration; (5) as the volume loading of MBR increases, the accumulation of high molecule organic substance and colloid increases, the membrane permeate COD concentration and paper filtered COD concentration increase too, meanwhile the water flux reduces; (6) when the sludge retention time of activated sludge of MBR increases, the accumulation of high molecule organic substance and colloid reduces, the membrane permeate COD concentration and paper filtered COD concentration reduce too, and the water flux increases; (7) comparing with the conventional biological process, the microbial activity is higher, but the microbial species is less.

Aerobiosis↗
PubMed2001

[Pulsatile rotary pumps with low hemolysis].

As is well known, a pulsatile flow is important in assisted-circulation but it is difficult to produce a pulsatile flow with rotary pump, because excessive hemolysis will be generated. The authors have found that the turbulent shear is the main factor for red cell damage and therefore the key point of pulsatile rotary pumps is to reduce the turbulence by producing a pulsatile flow. In the authors' pulsatile axial pump, the pulsatile flow is obtained by axial reciprocation of constant rotating impeller; the rotation and reciprocation of the impeller are driven separately by a DC motor and a pneumatic device. Though a physiological pulsatile flow could be achieved and turbulence would not increase remarkably because the impeller rotates constantly, a second driver except a DC motor is nevertheless necessary, thus the system will become complicated. In the authors' pulsatile radial pump, a pulsatile flow is achieved by changing the rotating speed of the impeller periodically. Turbulence is minimized by a special design of twisted vanes which enable the blood flow to change its direction rather than its dimension during periodic change of rotating speed. Hemolysis tests demonstrated that the index of hemolysis(IH) of the author's pulsatile radial pump is 0.020, with is slightly more than that of the author's nonpulsatile radial pump(IH = 0.015). Animal experiments indicated that the pulsatile radial pump can assist the circulation of calves for several months without harm to blood elements and organ functions of the recipients.

Animals↗
PubMed2000

Development of a transgenic mouse that overexpresses a novel product of the growth hormone-releasing hormone gene.

The GH-releasing hormone (GHRH) precursor molecule contains a 30-amino acid C-terminal region that has been designated GHRH-related peptide (GHRH-RP). To begin to understand the physiological role of GHRH-RP, transgenic (Tg) mice that constituitively express this peptide were developed. To generate these mice, a transgene (SS-RP) was constructed by overlap primer extension PCR. This transgene, under the control of the mouse phosphoglycerate kinase gene, selectively expresses GHRH-RP, but not GHRH. Western blot analysis confirmed that the transgene produces GHRH-RP. Animals were evaluated for the effect of excess GHRH-RP on growth, fertility, behavior, stem cell factor (SCF) expression, and hematopoiesis. Northern blot and RT-PCR were used to demonstrate ubiquitous expression of the transgene in tissues from GHRH-RP Tg animals. These tissues also had marked overexpression of SCF messenger RNA compared with controls. Tg animals had significantly increased cell cycling for granulocyte-macrophage, erythroid, and multilineage progenitor cells. Transgenic animals did not differ from control mice in their growth, fertility, or behavior. These findings demonstrate, for the first time, that in vivo the C-terminal peptide of the pro-GHRH molecule is a biologically active peptide that is capable of stimulating the expression of SCF and hematopoiesis in vivo and suggests that GHRH-RP may play a role in normal blood cell development.

Animals↗
PubMed2000

[Effect of various assist pumps on recovering the ventricular function].

With the authors' diaphragm pump and pulsatile as well as nonpulastile impeller pumps, and the clinically used Sarns Roller, both left ventricular assist and biventricular assist experiments were performed on mini pigs and calves. The results demonstrate that the pulsatile impeller pump is the best assist pump for recovering the heart function, because it maintains the pulsatility of aortic pressure by heart failure and thus increases the circulation volume, and it enlarges the diastolic pressure so as to increase the perfusion in coronary artery because it has no backflow.

Animals↗
PubMed1999

[Changes of glutamate and GABA in cerebrospinal fluid of patients with pneumonia complicated with central nervous system damage].

Glutamate(Glu), gamma-aminobutyric acid(GABA), and malondialdehyde(MDA) in cerebrospinal fluid (CSF) were measured in 18 children with pneumonia complicated with central nervous system(CNS) damage, 14 children with pneumonia without CNS damage, and 7 children with hypocalcemic tetany. The concentration of Glu and MDA and the ratio of Glu/GABA in CSF of pneumonia without CNS damage were significantly higher than the others. The ratio of Glu/GABA in CSF of the children with pneumonia with consciousness obstacle after convulsion was higher than that without consciousness obstacle after convulsion. These results suggest that Glu and free radicals may play a critical role in the CNS damage caused by pneumonia, however GABA may reduce the CNS damage caused by pneumonia.

Brain Diseases↗
PubMed1998

[VP-16 and VM-26 plus platinum drugs combined with radiotherapy in the treatment of small cell lung cancer].

OBJECTIVE: To compare the clinical efficacy of VP-16(etoposide) with VM-26(teniposide) both plus platinum drugs combined with radiotherapy in the treatment of patients with small cell lung cancer(SCLC). METHODS: Seventy-four cases of SCLC were studied retrospectively. Forty-three patients were treated with VP-16 + DDP + CTX or VP-16 + DDP, the other 31 patients were treated with VM-26 + DDP or VM-26 + Carboplatin. The treatment of both groups was combined with radiotherapy. RESULTS: There was no significant difference between VP-16 and VM-26 groups in response rate, 2-year-survival rate, and brain metastasis rate. But the blood toxicity was more serious in VM-26 group than in VP-16 group; 3-4 stage toxicity rate was 58.06% versus 27.91%. CONCLUSION: The results indicate that both VP-16 and VM-26 combined with platinum drugs were effective chemotherapy protocols. The authors suggest choosing VP-16 protocols as the first choice for previously untreated SCLC patients.

Adult↗
PubMed1998

[The animal experiments and clinical trial of impeller pump used as left ventricular or biventricular assist device].

The authors' impeller pump as a left ventricular or biventricular assist device was evaluated in animal experiments and clinical trial. Three calves survived over 6 weeks in left ventricular assist experiments and neither blood damage nor organ dysfunction of the animals was detected. In clinical trial, the pump supported both the greater and lesser circulation of a 6-year-old child with trilogy of Fallot and low output syndrome after open heart surgery. In 43 hours the pump worked properly. The pump weighing 240 g can perform either in pulsatile or in nonpulsatile mode. In pulsatile pumping, the impeller changes its rotating speed periodically by introducing a square wave form voltage into the motor coil.

Animals↗
PubMed1995

[Cell-mediated immune function in NPC patients treated with cimetidine].

Cimetidine (CMD), an H2 receptor antagonist, was used in combination with radiation for the treatment of patirnts with nasopharyngeal cancer (NPC). In patients treated with radiotherapy alone, there was an increase in the number of CD4+ T cells and in NK cell activity. In patients received combined treatment of radiation and CMD, in addition, there was a decrease in CD8+ T cells with an increase in CD4/CD8 ratio and an increase in IL-2 production. The NK cell activity was also stronger in the latter group. The results suggest that CMD helps restore cell-mediated immunity in NPC patients radiation treated.

Adjuvants, Immunologic↗
PubMed1995

[The reversing effect of HPV-16 E6E7 gene antisense plasmid on the HPV-16 positive human cervical carcinoma cells].

Antisense reconstruct, p16as E6E7Neo, harboring HPV-16E6E7 gene of which the expression is regulatable by dexamethasone was constructed. Calcium phosphate mediated transfection was employed to transduce this antisense reconstruct into HPV-16 positive CasKi cell line and HPV negative C-33A cell line (both derived from human cervical carcinoma) respectively. After dexamethasone was added into the culture medium to induce the expression of E6E7 antisense gene, the malignity of CasKi cells were reversed, while the growth characteristics and malignity of C-33A cells were unchanged. The results show that the reversing effect on CasKi cell is specific and mediated by inhibition of expression of E6E7 gene. It also demonstrated a more profound pathogenic role of HPV-16 E6E7 gene in the tumorogenesis of cervical carcinoma and provides a possibility for gene therapy of this tumor.

Animals↗
PubMed1994

[Gas chromatographic analysis of C1-C6 fatty acids in rat fecal samples].

A gas chromatography procedure was performed to determine C1-C6 fatty acids in rat feces. Acidated fecal homogenate was extracted with ethyl ether-petroleum ether (1 + 1). After adding tetramethylammonium hydroxide to the extract, the quaternary ammonium salts of the fatty acids could react with ethyl bromide in the presence of N,N-dimethyl acetamide producing corresponding esters. The derived products were separated by the column packed with ethylene glycol succinate polyester and were determined with Flame ionization detector (FID). The extractive efficiencies of C1-C6 fatty acids from the fecal samples were 88.5%-100%, and the recoveries ranged from 82.4% to 110.8% with the coefficients of variation of 3.2%-10.9%. The detection limits were at 1ppm. The optimum conditions of esterification are discussed. The method is safe and rapid, and has been applied to the analysis of C1-C6 fatty acids in rat feces.

Animals↗
PubMed1994

[HPLC analysis of 2-(P-dimethylaminostyryl) pyridine methiodide concentration in plasma].

A reversed phase high performance liquid chromatography (RP-HPLC) method for determination of 2-(p-dimethylaminostyryl) pyridine methiodide (DSPM) concentration in rabbit plasma is reported. The stationary phase was YWG-C18H37. The mobile phase consisted of 80% CH3OH, 20% CH3COOH-CH3COONa buffer (pH 4.0, 0.20 mol/L) and (C2H5)2NH 25 mmol/L. Its flow rate was 1.0 ml/min. The column temperature and pressure was 28 degrees C and 10.13 MPa, respectively. The detect wavelength was 460 nm. The detection limit of DSPM was 2 ng or 0.08 mumol/L in plasma. The RSD (%) of within-day and between-days were less than 7%. A good linear relationship between peak area and DSPM concentration in plasma (0.68-13.65 mumol/L) was found (r = 0.9996).

Animals↗
PubMed1990

[Biphasic effects of caffeine on tension in isolated aorta of rat].

The dual effects of caffeine on the tension were observed in rat thoracic aorta. When the preparation was exposed to Tyrode's solution containing caffeine of 1, 5 and 10 mmol/L, the tension increased. In 1-2 min it slowly decreased to a level lower than the pre-caffeine tension. After norepinephrine (1 mumol/L) was added, caffeine produced a greater inhibitory effect and the contraction phase disappeared. The dual effects of caffeine were not affected by the vascular endothelium. In the Tyrode's solution containing NiCl2 2 mmol/L, the first addition of caffeine (10 mmol/L) or norepinephrine (0.1 mumol/L) caused a contraction. The one caused by norepinephrine was greater. A second addition of caffeine did not cause a contraction, but addition of norepinephrine at this time caused a small contraction. After the washout of norepinephrine which had caused a greater contraction, the addition of caffeine (10 mmol/L) did not cause a contraction. These results indicate that norepinephrine completely depletes caffeine-sensitive Ca2 stores but caffeine only partially depletes norepinephrine-sensitive Ca2+ stores.

Animals↗