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Biomedical subjects

B Y Li

Publications and source records attributed to B Y Li.

At least 55 records · Page 3Linked to original sources
PubMed1994

The relationship between the energy levels of shock waves and the degree of renal damage after ESWL: a prospective clinical matching trail.

In an attempt to understand the effects of high energy shock wave (HESW) on renal function, we studied prospectively 40 patients with nephrolithiasis in 4 groups, using same voltage with different numbers of shock wave therapy to identify the difference of effects on renal function. Stone burdens and position were similar in these groups. Each group received 1500, 2000, 2500 or 3000 pulses at 12.5 KV on JT-3 lithotripotor respectively. All the groups had significantly increased the levels of urinary NAG, beta 2MG, ALB and serum beta 2MG, which reached the highest values on 1-3 days after ESWL (P < 0.001), and then decreased to the pre-ESWL levels except urinary NAG in group C and D and serum beta 2MG which were still significantly higher (P < 0.05) than those before-ESWL on the 7th day after ESWL. There was significant correlation between either urinary NAG (gamma = 0.977, P < 0.05) or beta 2MG (gamma = 0.933, P < 0.001) with the number of shock wave. In addition, urinary NAG and beta 2MG increased significantly when the number of shock waves was over 2500 shots. These above findings suggest that shock wave had induced acute changes in renal functions and transient renal tubular damages, although these functional changes recovered within one week, and the tubular damage might last longer than 7 days, In order to avoid serious renal damage, it's necessary to limit the energy level of shock waves under 12.5 KV x 2500 shots by using JT-3 lithotriptor.

Acetylglucosaminidase↗
PubMed1992

Human ovarian epithelial cancer cells cultures in vitro express both interleukin 1 alpha and beta genes.

Ascitic fluid from human ovarian cancer patients often contains a large number of leukocytes along with tumor cells. Some of the recent evidence suggests that the ascitic fluid contains factors capable of inducing the growth of ovarian cancer cells in vitro and in vivo. While these factors have not yet been completely characterized, growth factors secreted by the tumor cells could influence the tumor growth by paracrine and autocrine mechanisms. Earlier, we reported that ovarian epithelial cancer cells produce macrophage colony-stimulating factor. It appears that these tumor cells produce more than one cytokine. Identifying the various products secreted by the tumor cells would provide valuable information needed to understand the biology of ovarian cancer. In the present study, evidence is provided for the first time that five different human ovarian epithelial tumor cell lines and tumor cells isolated from the ascitic fluid of four cancer patients express interleukin (IL) 1 alpha and beta genes constitutively. Production of the lymphokine was determined by analyzing the cellular RNA for IL-1-related transcripts and by immunological assays. Ovarian cancer cells also secrete another pleiotropic cytokine, IL-6, constitutively. In many systems, IL-1 induces the expression of the IL-6 gene. To determine whether the basal levels of IL-6 production are dependent on the endogenous IL-1, neutralization studies were carried out. Addition of antibodies to IL-1 did not decrease the levels of IL-6 secreted by the cancer cell lines. These results suggest that multiple cytokines are produced by ovarian cancer cells and that the endogenous IL-1 may not be directly involved in the regulation of IL-6 gene expression in these cells.

Ascitic Fluid↗
PubMed1992

High-level expression and simplified purification of recombinant ricin A chain.

Ricin toxin is a glycoprotein which catalytically inactivates eukaryotic ribosomes by depurination of a single adenosine residue from the 28S ribosomal RNA. The enzymatic activity is present in the A chain of the toxin molecule, whereas the B chain contains two binding sites for galactose. Since it is highly potent in inhibiting protein synthesis, the A chain is used to prepare cytotoxic conjugates effective against tumor cells. Such chimeric proteins are highly selective and have a wide range of clinical applications. Extensive preclinical studies on these conjugates require large amounts of purified A chain. Native ricin A chain is heterogeneous, since plants produce a number of isoforms of ricin toxin. Purified, native preparations often contain two types of ricin A chain which differ in the extent of glycosylation. By cloning and expressing the gene of A chain, one could obtain homogeneous toxin molecules devoid of carbohydrates. In addition, structural changes in the toxin polypeptide could be introduced by in vitro mutagenesis, which can improve the pharmacological properties and antitumor activity. Earlier methods of expression strategies using Escherichia coli have yielded only moderate levels of expression. In the present study, the coding region of ricin A chain was cloned into pET3b, a high-level expression vector under the control of the T7 promoter. Recombinant ricin A chain produced by this construct has an additional 14 amino acid residues at the NH2 terminus. Subsequently, a NdeI site was created at the 5' end of the gene by oligonucleotide-directed mutagenesis. The modified fragment was then introduced into pET3b vector to produce toxin polypeptide identical to the native sequence.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1992

[The effect of glycosaminoglycans in the pulmonary interstitial fibrosis development].

The pulmonary interstitial fibrosis was caused by injecting Bleomycin into mouse trachea. After the injection, the volume of glycosaminoglycans (GAG) in bronchoalveolar lavage fluid and lung tissues was increased. The observation of histochemical stain and electron microscope showed that the distribution of GAG in lung tissues was varied at different time after the injection, and related to the volume of collagen proteins and the formation of pulmonary interstitial fibrosis.

Animals↗
PubMed1992

Effects of berbamine on contraction and Ca2+ influx of pig basilar artery.

Effects of berbamine (Ber) on KCl- and 5-HT-induced contraction of basilar artery (BA) of pigs were studied in vitro. Ber relaxed markedly KCl-induced contraction of BA (IC50 = 4.63 mumol.L-1) and its effect was antagonized by increasing the concentration of extracellular Ca2+; Ber inhibited 5-HT-induced contraction of BA, showing significant inhibition of sustained tonic contraction (STC) (IC50 = 0.64 mumol.L-1) whereas the initial fast phasic contraction (FPC) was relatively unaffected (IC50 = 19.8 mumol.L-1); the 5-HT-induced contraction of BA was dependent on the concentration of extracellular Ca2+, especially STC. The results of Ca2+ withdrawal and replacement indicated that STC was due to 5-HT-stimulated Ca2+ influx, while 5-HT-induced release of intracellular Ca2+ resulted in FPC. Ber 0.8 mumol.L-1 produced markedly inhibitory effect on Ca2+ influx induced by 5-HT (P < 0.01). The effects of Ber were similar to those of nimodipine (Nim). The present results suggested that Ber has antagonistic effect on the potential sensitive channels (PSC) and the receptor operated channels (ROC).

Alkaloids↗
PubMed1992

[High energy shockwave-induced acute changes in renal function].

Attempting to understand the effects of HESW on renal function, we studied prospectively 40 patients with nephrolithiasis in 4 groups, using different number of pulsation and the same voltage to identify different effects. Stone burdens and position were similar in these groups. Each group received 1,500, 2,000, 2,500, or 3,000 pulses respectively at 12.5 kV from JT-3 lithotripter. In all groups, the levels of urinary NAG, beta 2MG, ALB and serum beta 2MG were significantly increased at day 1-3 after ESWL (P < 0.001), and then decreased to the levels of pre-ESWL except serum beta 2MG and urinary NAG levels of group C and D at day 7 after ESWL, which were significantly higher (P < 0.05) than those of pre-ESWL. There was significant correlation between either urinary NAG (r = 0.977, P < 0.05) or urinary beta 2MG (r = 0.933, P < 0.001) and the number of pulses at day 3 post-ESWL. In addition, there was a significant difference in urinary NAG levels between group D and group A, B or C at day 3 post-ESWL, and the same was true in urinary beta 2MG levels between group C or D and group A or B. These findings suggested that shock wave induced acute changes in renal function and transient renal tubular damages, and that the tubular damages might last longer more than 7 days, although these functional changes recovered within one week. The changes were related to the energy levels of shock wave, and the degree of renal damage would increase when the energy level was above 12.5 kV x 2,500 pulses.

Acetylglucosaminidase↗
PubMed1991

Development of two new monoclonal antibodies reactive to a surface antigen present on human ovarian epithelial cancer cells.

Monoclonal antibodies which bind selectively to cancer cells are currently used for tumor localization and for targeting cytotoxic reagents. The success of these approaches depends on the specificity of the antibody and its reactivity to a majority of the tumor samples. Frequently, monoclonal antibodies are generated by immunizing mice with antigenic preparations from a single tumor cell line. Antibodies generated under these conditions often react to a narrow range of tumors. In the present study, mice were immunized with multiple ovarian cancer cell lines in a sequential manner to amplify the immune response against common antigenic determinants expressed in these cell lines. Spleen cells from the immunized mice were then fused with NS-1 myeloma cells to establish hybridomas. Two cell lines were selected on the basis of their selective reactivity to ovarian cancer cells after extensive screening. Monoclonal antibodies OVX1 and OVX2 bound to all 5 ovarian carcinoma cell lines tested and did not bind to normal fibroblast cells. These antibodies recognized a unique antigenic determinant present in ovarian and breast cancer cells. Cross-blocking studies showed that the binding of OVX1 and OVX2 is not displaceable by 10 other previously described anti-ovarian antibodies including OC125. In immunocytochemical studies, OVX1 reacted to a majority of ovarian cancer tissues (17 of 20) and did not bind to normal ovarian tissues. Preliminary results indicate that OVX1 and OVX2 antibodies are directed to a high molecular weight antigen. These antibodies could be used in the preparation of cytotoxic conjugates.

Animals↗
PubMed1991

Effects of berbamine on hemodynamics and myocardial reperfusion injury in isolated working rabbit hearts.

The isolated working rabbit hearts perfused with Tyrode's buffer solution persisted working in good condition at least up to 70 min. Berbamine (Ber) 3 mumol.L-1 significantly changed the hemodynamic parameters and reduced cardiac functions. The effects of Ber appeared in a dose-dependent manner. Reperfusion following 30-min of global ischemia aggravated the myocardial damages induced by ischemia, and the parameters of cardiac functions in working hearts markedly reduced and did not restore even at 20 min of reperfusion. Ber 1 mumol.L-1 reduced the myocardial ischemic reperfused damages and restored all parameters to the level of preischemia within 10 min of reperfusion, and this situation of working hearts also lasted 40-50 min. The present results showed that Ber could protect myocardium against ischemic reperfused damages, promote the recovery of cardiac functions and prolong the efficient working period in isolated working rabbit hearts.

Alkaloids↗
PubMed1990

Influence of morphine microinjected into head of caudate nucleus on electric activities of nociceptive neurons in parafascicular nucleus of rat thalamus.

Morphine (8 micrograms/microliter) was injected into the head of the caudate nucleus (CN). The pain-discharges of the pain-excitation neurons (PEN) in the parafascicular nucleus (Pf) were inhibited, ie, decreasing in frequency of pain-discharges and lengthening in latent period of pain-discharges. The inhibitory effect of the pain-inhibition neurons (PIN) in the Pf induced by noxious peripheral stimulation were relieved, ie, increasing the firing rate and shortening the inhibitory duration. The opiate receptor antagonist naloxone (0.75 mg/kg, ip) blocked the above effects of morphine. These results suggest that the intracaudate opioid peptide system play an important role in the modulation of pain information in the Pf of thalamus.

Animals↗
PubMed1988

Effects of K salt or a potassium blocker on gossypol-related hypokalemia.

Gossypol was found to be an effective male contraceptive. The most serious side effect of gossypol contraception was the presumed lowering of serum potassium levels. The purpose of this present randomized and controlled study was to evaluate the merit of ingesting K salt or a potassium blocker while using gossypol. Results indicated that supplementation of K salt does not cause a reversal of the effect of gossypol on serum potassium levels and the blocker triamterene does not prevent loss of serum potassium.

Analysis of Variance↗