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Biomedical subjects

J Tian

Publications and source records attributed to J Tian.

At least 181 records · Page 10Linked to original sources
PubMed1993

Parathyroid hormone-parathyroid hormone related protein receptor messenger RNA is present in many tissues besides the kidney.

Parathyroid hormone (PTH) acts on a large number of cells derived from many different tissues that are not traditional targets (kidney and bone) for their action. Also, the acute exposure of many of these cells to PTH resulted in the generation of cAMP. These observations are consistent with the presence of PTH receptors on these cells. However, there is no evidence that the cells that are not traditional targets for PTH, express the receptor of the hormone. The cloning of the PTH-PTH related protein (PTH-PTHrP) receptor provided the tool to examine whether these cells contain the mRNA for this receptor. Poly A+RNA from a variety of rat tissues was probed with a 1,200-bp fragment of the cDNA of the PTH-PTHrP receptor by the Northern blot technique. We found that mRNA for the PTH-PTHrP receptor is present in the heart, brain, spleen, lung, liver, skeletal muscle, kidney and testis. Transcripts of 2.4 kb were found in all these tissues with the strongest expression in the kidney. In addition, smaller RNAs were detected in the kidney (approximately 1.8 kb) and testis (1.5 kb). These results indicate that many cell types express the PTH-PTHrP receptor gene. The data provide a possible explanation for the direct effects of PTH on so many cells and for the understanding of the harmful effects of chronic excess of PTH on the function of many organs in chronic renal failure.

Animals↗
PubMed1992

Formation of the excited ferryl species following Fenton reaction.

A concomitant chemiluminescence burst can be detected when hydrogen peroxide is injected into the solution containing either free or chelated ferrous iron. The duration of the burst is slightly longer than the time for the oxidation of Fe2+. The luminescence intensity is a quadratic function of the initial concentration of H2O2 and is dependent on Fe2+ concentration. The scavengers of hydroxyl radical effectively inhibit, while the previously added ferric ions enhance, the luminescence. It is proposed that the excited species responsible for the luminescence is created by the reaction of hydroxyl radical with ferric iron. The theoretical analysis based on such a mechanism can fairly well interpret the experimental observation. The present study suggests that an excited ferryl species may be formed in Fenton reaction.

Free Radical Scavengers↗
PubMed1992

Intra-hepatic-arterial infusion of misonidazole--an experimental study of regional radiosensitisation by intraarterial embolisation.

The purpose of this study was to generate a selective radiosensitising effect by the intra-hepatic-arterial infusion of misonidazole (MISO). MISO (10 mg) was infused after transcatheter hepatic-arterial embolisation into the livers of rabbits bearing VX2 liver cancer. This procedure was followed by 15 Gy electron irradiation. Evaluation of tumour volume and histological examination was carried out on the 7th day after treatment. The greatest tumour response was obtained in the group which received MISO followed by radiation and was characterised by extensive fibrosis around the tumour and nearly complete tumour necrosis. Liver cell regeneration was also noted in adjacent liver tissue. The advantages of regional infusion of MISO following hepatic-arterial embolisation are: (1) Selectivity increased radiosensitivity of liver cancer alongside very low drug concentration in the plasma. (2) Reduced or absent deleterious side effects of MISO with higher tumour/normal tissue ratios of drug concentration. (3) Reduced cost due to the lower dosage of MISO required for regional infusion.

Animals↗
PubMed1992

Postural stability in patients with Huntington's disease.

We characterized postural stability in patients with Huntington's disease (HD) by examining their ability to use different sensory cues to maintain balance and by recording their automatic postural responses to externally applied perturbations. Our HD patients, like normal subjects, depended more on proprioceptive than on visual cues to maintain balance. HD patients, however, developed more sway than normal subjects when proprioceptive cues, or when proprioceptive cues and vision, were altered. Thus, HD patients showed a defect in using vestibular information alone to maintain normal postural stability. The onset of compensatory motor responses in the lower extremities following sudden translations of the support surface was delayed by 30 to 60 msec in HD patients as compared with normal subjects. HD patients also had more sway and falls during unexpected rotations of the support surface, although they could appropriately reduce their motor responses on the next trial.

Adult↗
PubMed1992

[Mechanisms and therapeutic effect of Cordyceps sinensis (CS) on aminoglycoside induced acute renal failure (ARF) in rats].

Nephrotoxic ARF model of rat was induced by IP injection of either Gentamycin or Kanamycin and treated with CS. The results of study showed that the simultaneous administration of CS with Gentamycin could protect the proximal tubular cells from Gentamycin toxicity and the use of CS after the establishment of Kanamycin nephrotoxic ARF could prompt an earlier recovery from ARF as compared with the control group. The possible mechanisms of CS on ARF include: (1) protecting tubular cell sodium pump activity; (2) attenuating tubular cell lysosome overfunction stimulated by phagocytosis of aminoglycoside; (3) decreasing tubular cell lipoperoxidation in response to toxic injury.

Acute Kidney Injury↗
PubMed1992

[Analysis of the linear migration of the radionuclide along meridians in perfused extremities of monkey].

On the basis of researches in human body, further experiment in monkeys was conducted and the result has demonstrated that: 1. There was a close and complicated relation between the migration of 99mTc injected into acupoints and the blood circulation. 2. The location of the migration was mainly in the subcutaneous lay. 3. There were no direct relationship between the migration and periphery nerve system.

Animals↗
PubMed1992

[Vibrio cholerae toxin B subunit gene expressed in a Salmonella vaccine strain].

This paper reports that the V. cholerae toxin B subunit (ctx B) gene was inserted into pYA 248 plasmid with the aspartate beta-semialdehyde dehydrogenase (asd)gene and the recombinant plasmid was transformed into S. typhimurium deleting asd gene. Results showed that ctx B gene was highly expressed and secreted into midium. This strain was able to colonize in the intestinal epithelium. Oral immunity and general immunity could produce antibodies at high level and enhance cellular immune responses. The animals orally inoculated with S. typhimurium x 4072 (pYA-ctx B) vaccine had remarkable protection against virulent V. cholear 569B strain and S. typhimurium strain. Use of such system provides useful method for oral vaccine.

Animals↗
PubMed1992

[A study on the effect of stimulating auricular points on the biliary tract].

We have developed an animal model to study the effect of stimulating auricular points on the function of hepato-biliary system. The preliminary result shows that 14 of 18 rabbits acquired a marked increase (P less than 0.05) in the amount of heptic bile secretion 3 min and 7 min after point No. 3 stimulated with 58V.

Acupuncture Points↗
PubMed1991

Effect of digoxin on contractility and symptoms in infants with a large ventricular septal defect.

The effect of digoxin on contractility and symptoms in infants with a large ventricular septal defect (VSD) is controversial. Nineteen infants with symptoms of congestive heart failure due to a VSD were studied with load-independent indexes during 4 study periods: (1) before any medication; (2) while on chronic diuretics; (3) while on both diuretics and digoxin; and (4) while on diuretics alone, to determine if digoxin: (a) increases "contractility" when added to diuretic therapy; and (b) improves symptoms. Symptoms, signs (heart and respiratory rates, and weight gain), shortening fraction, preload (left ventricular end-diastolic dimension), afterload (left ventricular end-systolic wall stress) and contractility were measured at each period. The difference between the measured and predicted velocities of circumferential fiber shortening for the measured left ventricular end-systolic wall stress served as an index of contractility. Eighteen infants also underwent catheterization. Mean pulmonary-to-systemic blood flow ratio was 3:1. When digoxin was added to diuretics, contractility index was significantly greater than in control subjects (0.13 +/- 0.15 vs 0.0 +/- 0.12 circ/s, p = 0.04). When patients were again on diuretics alone (after discontinuation of digoxin), contractility index was no longer different. Symptoms and signs were not significantly improved by either diuretics or digoxin. It is concluded that in infants with a large left-to-right VSD shunt and receiving digoxin and diuretics, contractility index was significantly greater than in control subjects. However, neither diuretics alone nor in combination with digoxin improved symptoms significantly.

Digoxin↗
PubMed1991

Changes in cardiac function during extracorporeal membrane oxygenation for persistent pulmonary hypertension in the newborn infant.

The effects of extracorporeal membrane oxygenation (ECMO) on cardiac function and its determinants (preload, afterload, contractility, and heart rate) are largely unknown, although some evidence exists that function may decrease. To determine whether cardiac function decreases and what changes in the determinants take place during and after ECMO, we observed 26 newborn infants with persistent pulmonary hypertension. Serial echocardiograms were performed before ECMO, during maximum cardiopulmonary bypass, and after ECMO. Cardiac function was assessed by using standard echographic ejection phase indices (shortening fraction and cardiac output). Heart rate, preload (left ventricular end-diastolic dimension and area), afterload (left ventricular end-systolic wall stress), and contractility (relationship between velocity of circumferential fiber shortening and wall stress) were also measured. Ejection phase indices significantly decreased during ECMO (shortening fraction 33% to 25%, cardiac output 205 to 113 ml/kg/min; p less than 0.05) and returned to normal after ECMO (shortening fraction 26% to 34%, cardiac output 107 to 240 ml/kg/per minute; p less than 0.05). Heart rate also significantly decreased during ECMO (158 to 118 beats/min; p less than 0.05). Preload significantly increased after ECMO (left ventricular end-diastolic dimension 1.4 to 1.6 cm, left ventricular end-diastolic area 1.9 to 2.2 cm2; p less than 0.05). There were no significant changes in contractility and afterload during any study period. We conclude that, although left ventricular ejection phase indices and heart rate decreased during ECMO, these changes were transient and resolved when bypass was terminated. Contractility and afterload did not appear affected by bypass.

Bacterial Infections↗
PubMed1991

[Blood supply of hepatic carcinomas and its clinical significance].

Parasitic blood supply in 85 patients with hepatic carcinoma was demonstrated by selective angiography and CT. The hepatic carcinomas in the posterior segment of the right hepatic lobe and the lateral segment of the left hepatic lobe were partially fed by the inferior phrenic arteries in 48 patients. The hepatic carcinomas in the inferior portion of the right hepatic lobe were partially fed by the omental arteries in 37 patients. The development of parasitic blood supply depends more upon the location of the tumor than the occlusion of hepatic artery. Although the hepatic artery is occluded, the tumor may still receive blood supply from its parasitic arteries and continue to grow steadily. Therefore, in patients with double arterial blood supply, transcatheter double arterial (hepatic artery and parasitic arteries) infusion and embolization (TDAIE) should be applied for treatment. TDAIE was used in 33 of 85 cases and the preliminary result was quite satisfactory.

Adult↗
PubMed1991

[Effects of Cordyceps sinensis, rhubarb and serum renotropin on tubular epithelial cell growth].

Primary cultured rat tubular epithelium was utilized to investigate the effect of Cordyceps sinensis (CS) on cellular proliferation and metabolism. Judging from incorporation rate of 3H-TdR, it was found that the addition of serum containing CS metabolites into the culture media could promote the DNA synthesis of tubular cells profoundly (P less than 0.001). In association with its beneficial effects on gentamycin nephrotoxity in vivo study, it is indicated that CS could enhance the regeneration of injured tubular cells. In addition, sera obtained from 5/6 nephrectomized rats (5/6 NT) and rhubarb treated rats were studied to see their effects on tubular cells growth. The results showed that the serum of 5/6 NT rats could promote the DNA synthesis of tubular epithelium, while the presence of experimental serum of rhubarb in culture median markedly inhibited the DNA synthesis of cells.

Animals↗
PubMed1991

[Model of stimulus train-induced bursting in rat hippocampal slice and the effect of L-glutamate on it].

A train of pulses (60 Hz, pulse duration 100 microseconds, train duration 2s, 2-3 fold maximal intensity) were applied to the CA3 stratum radiatum fiber pathway in rat hippocampal slices in vitro. Recordings of the field potentials were made from the stratum of CA3 pyramidal cells in response to these pulses so that the model of stimulus train-induced bursting (STIB) could be studied. It was a new and valuable model of epileptiform activity in hippocampal slices in vitro and the effect of L-glutamate (Glu) on STIB was also studied. Results showed that: 1. The number of train stimulus for a stable STIB averaged 5.5 +/- 2.1; the induced number of population spikes (PS) increased with an average in 5.2; and the STIB activity was long-last, persisting for up to 3-4 hours following the last train. 2. Superfusions of Glu in concentrations of 1, 2, and 3 mmol/L in hippocampal slices produced inhibition of STIB in CA3, but the first antidromic PS was unaffected, suggesting the site of inhibition is postsynaptic. The mechanisms related to the genesis of STIB and its inhibition by superfusion of Glu were discussed.

Animals↗
PubMed1991

[Cloning and expression of the cholera toxin B subunit gene].

The CT-B gene-expressing plasmid pXB1 and modified pXB2 were constructed using recombinant DNA techniques. These resulted in high CT-B gene expression in E. coli (280-350 ng/ml), with CT-B accounting for 71.5% of total extracellular protein. The results of CT-B expression kinetics showed that the CT-B product levels reached a peak after 24 h in culture. Certain concentrations (100 micrograms/ml) of MgCl2, L-histidine and asparagine can increase the CT-B product level by 10%-25%. The binding of the expressed CT-B product to GM1 receptor on free or live cell membranes was identified by GM1-ELISA, CHO cytotoxicity test, indirect immunofluorescence, and the rabbit ileal loop test. No toxic response to cells or rabbits was detected.

Animals↗
PubMed1990

Erythrocyte fatty acids, plasma lipids, and cardiovascular disease in rural China.

Cardiovascular disease (CVD) mortality (coronary heart disease, hypertensive heart disease, and stroke), plasma lipids, and red blood cell fatty acid composition were examined in an ecologic study in 65 rural counties in the People's Republic of China. Means of plasma total cholesterol, triglyceride, low-density-lipoprotein (LDL) cholesterol, and high-density-lipoprotein (HDL) cholesterol concentrations were substantially lower and the ratio of HDL cholesterol to total cholesterol was higher in this Chinese population than in Western populations. Mortality rates for CVD in China were well below Western values. Within China neither plasma total cholesterol nor LDL cholesterol was associated with CVD. A strong inverse correlation between red blood cell oleate concentrations and CVD was observed. However, red blood cell oleate concentrations were not associated with plasma cholesterol but were strongly negatively associated with arachidonate concentrations, suggesting potential diminution of CVD by oleate through reduced platelet aggregability. The results indicate that geographical differences in CVD mortality within China are caused primarily by factors other than dietary or plasma cholesterol.

Adult↗
PubMed1990

[Effect of several factors on enzymic activity and antigenicity in chemical modification of L-asparaginase].

Acetic anhydride, dextran and monomethoxypolyethylene glycol and different modification methods were used for modification of L-asparaginase to maintain enzyme activity and completely remove its antigenicity. The results showed that the macromolecular modifiers PEG and dextran were better than the small molecular modifier acetic anhydride. For maintenance of enzyme activity and removal of antigenicity modification in the presence of substrate was better than absence of substrate and activated PEG2 was better than activated PEG1. When PEG2-L-asparaginase was modified in the presence of substrate, its antigenicity was completely removed, while more than 30% of native enzyme activity were still retained.

Acetic Anhydrides↗
PubMed1990

[A new monoclonal antibody against human tubular brush border: preparation and its application in membranous nephropathy].

A new monoclonal antibody (McAb) against human tubular brush border was successfully prepared by authors using the hybridoma technique. The McAb produced was identified to be isotype of IgG1 by IF and SDS-PAGE assay. It was unique for its purity and specificity. To demonstrate the clinical usefulness, the McAb was applied for immunopathological study in 94 cases of renal biopsy of glomerular diseases. This McAb was distinguished by its specific deposition along the human tubular brush border and the subepithelial region in certain type of glomerular disease, particularly the MGN. Identification of this McAb might contribute to the immunopathological diagnosis of GN.

Animals↗