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Biomedical subjects

H Liu

Publications and source records attributed to H Liu.

At least 1,081 records · Page 60Linked to original sources
PubMed1994

Stable and temperature-sensitive transformation of rat kidney epithelial cells suppresses expression of acidic fibroblast growth factor 1 but activates secretion of fibroblast growth factor 3 (int-2) and vascular endothelial growth factor.

Rat kidney proximal tubule epithelial cells (RPTE) in primary culture express acidic fibroblast growth factor 1 (FGF-1). Transformation of RPTE by SV40 (SV-RPTE) suppressed FGF-1 expression but activated secretion of FGF-like factor(s). SV-RPTE conditioned medium contained growth-promoting activity for SV-RPTE and human umbilical vein endothelial cells, indicating that both autocrine and angiogenic factors were secreted. Reverse transcriptase-polymerase chain reaction and Northern analysis for various FGFs showed that only FGF-3, also known as int-2, mRNA was expressed in SV-RPTE. In addition, expression of mRNA for the heparin-binding angiogenic factor vascular endothelial growth factor (VEGF) increased dramatically in SV-RPTE. Physical characterization of the activity in the SV-RPTE conditioned medium suggested that FGF-3 and VEGF contributed the autocrine and angiogenic activities, respectively. We also investigated FGF-3 and VEGF secretion in temperature-sensitive (ts) SV40-transformed RPTE. tsSV-RPTE had transformed properties resembling those of SV-RPTE only at the permissive temperature (33 degrees C), e.g., increased growth potential and anchorage-independent growth. FGF-1 was expressed only at the nonpermissive temperature. VEGF mRNA levels and secretion of the human umbilical vein endothelial cell growth-promoting activity were reduced by switching tsSV-RPTE cells from 33 degrees to 39 degrees C. However, FGF-3 mRNA levels were not affected significantly by the temperature switch suggesting that activation of VEGF and FGF-3 occurs through different mechanisms. These results indicate that FGF-1 expression in RPTE is suppressed by SV40 transformation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Mutagenicity and induction of drug-metabolizing enzyme activity by LPG combustion particulates in rats.

Methylene chloride extracts of particulates from liquefied petroleum gas (LPG) combustion appliance were studied by using Ames test, micronucleus test and inducibility of pulmonary and hepatic aryl hydrocarbon hydroxylase (AHH) and glutathione S-transferase (GST) in rats. The extracts showed mutagenicity for Salmonella typhimurium strain TA98 and its derivatives TA98NR and TA98/1,8-DNP6 with or without S9 mix. The revertants in strains TA98NR and TA98/1,8-DNP6 were less than 40% and 50% of that in strain TA98 without S9 mix, respectively. Positive results were obtained in mouse bone marrow micronucleus assay. Intratracheal instillation of the extracts led to increase in pulmonary (but not hepatic) AHH and GST activities in rats. It was seen that AHH was more sensitive than GST to induction by the extracts.

Animals↗
PubMed1994

[Nasal endoscopic middle meatal antrostomy].

Middle meatal antrostomy under nasal endoscope, a functional procedure which conforms to paranasal sinus physiology, has provided a new approach to reestablishing the ventilation and drainage of nasal cavity and paranasal sinus. A 3-15 month's follow-up of 75 patients with chronic sinusitis and polyps who had undergone endoscopic sinus surgery shows a higher patency rate of 86.7% and a lower closure rate of 13.3%. While for patients who received inferior meatal antrostomy the patency rate was 54.7% and the closure rate 45.3%. There was a significant difference (P < 0.01) between the two groups in patency rate and closure rate respectively. So the antrostomy of middle meatus appears to be better than that of inferior meatus. The clinical significance of middle meatal antrostomy on the basis of anatomy and physiology of paranasal sinus is emphasized in discussion.

Adolescent↗
PubMed1994

Mechanism and etiology of primary chronic angle closure glaucoma.

The ocular anatomic features, pupil-blocking force, status of angle synechiae closure and positivity of provocative tests were compared between the primary chronic angle closure glaucoma (PCACG) and primary acute angle closure glaucoma (PAACG) by using ultrasonic biometry, computerized anterior ocular segment image processing technique, gonioscopy and provocative tests. The studies showed that the anterior chamber depth of PAACG were shallower than that of PCACG; the pupil-blocking force of PAACG was stronger than that of PCACG; the status of angle synechiae closure of PCACG were mainly creeping synechiac closure; the positivity of mydriasis test was much higher (46.01%) in PCACG than that (6.8%) in PAACG after iridectomy. These facts suggest approximately half of the PCACG cases may be mult-mechanism to contribute to the angle closure besides the mechanism of pupillary block. Therefore, the authors emphasis that the pupillary block must be eliminated as well as the other mechanism for the treatment of PCACG and finally, a criteria of diagnosis and principles of management of PCACG were proposed.

Adult↗
PubMed1994

[Evaluation of posttraumatic hearing loss].

In this study a comprehensive audiometry was applied to detect the hearing loss in 400 patients (531 ears) with difficult-to-test hearing loss induced by ear or skull injury. It was found that the real PTA detectable rate reached 95.29% and the incidence of hearing loss was 82.11%, of which 68.81% were related to injury. The incidence of nonorganic deafness was 77.59%, i.e., the incidence of hearing loss exaggerated by patients was 57.25% (tested ears), simulated deafness was 16.20% and functional deafness was 4.14%. The principle of dealing with nonorganic deafness was discussed.

Adolescent↗
PubMed1994

[Effects of gamma-aminobutyric acid and bicuculline on the spontaneous discharge of the nucleus paragigantocellularis lateralis neurons in brainstem slices in rat].

The effects of iontophoretic application of gamma-aminobutyric acid (GABA) and its antagonist, bicuculline (BIC) on the spontaneous discharge of paragigantocellularis lateralis (PGCL) neurons and the influence of BIC on the effects of GABA were studied in brainstem slice in rat with multibarrel microelectrode techniques. Both GABA and BIC showed three types of effects, i.e., excitatory, inhibitory and unaffected; the percentage of each is 56.10%, 31.70%, 12.20% (for GABA) and 66.67%, 5.88%, 27.45% (for BIC) of the tested neurons, respectively. The inhibitory effect of GABA and excitatory effect of BIC are dose-dependent. In most of the neurons tested the response to GABA could be blocked by BIC. The results at cellular level suggest that there is endogenous GABA in PGCL and that there exists GABAA receptors on some of the PGCL neurons.

Animals↗
PubMed1994

Effect of phospholipase C and apolipophorin III on the structure and stability of lipophorin subspecies.

Four distinct subspecies of the insect hemolymph lipoprotein, lipophorin, that range in diacylglycerol (DAG) content from approximately 100 to 1000 molecules per particle, were treated with phospholipase C. Lipid analysis demonstrated that both phosphatidylcholine and phosphatidylethanolamine were hydrolyzed to DAG. Phospholipase C was used to remove 74-82% of the phospholipid of different lipophorins and these were analyzed for aggregation. Low density lipophorin (LDLp), the largest subspecies, with a diameter of approximately 23 nm, developed turbidity (monitored by sample absorbance at 340 nm) suggesting the formation of lipoprotein aggregates. High density lipophorin-adult (HDLp-A) and high density lipophorin-wanderer 1 (HDLp-W1) also displayed an increase in A340 when incubated with phospholipase C, although the maximal increase observed was considerably less than that for LDLp on a per particle basis. Phospholipase C caused only a minimal increase in A340 in a fourth subspecies, high density lipophorin-wanderer 2 (HDLp-W2), which contains an even lower amount of DAG. Electron microscopy was used to evaluate changes in particle morphology as a result of phospholipid depletion. HDLp-W2 and HDLp-W1 showed signs of progressive aggregation and particle fusion. A similar aggregation/fusion was seen in the case of high density lipophorin adult (HDLp-A) while LDLp samples contained multiple aggregation/fusion foci and resultant very large particles. In the presence of exogenous apolipophorin III (apoLp-III), phospholipase C-induced lipophorin aggregation/fusion was prevented. Electron microscopy of LDLp and HDLp-A samples revealed that apoLp-III-stabilized, phospholipase C-treated particles had a morphology similar to that of control particles.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Cobaltous chloride-mediated induction of rat hepatic tryptophan 2,3-dioxygenase: implications for the use of the enzyme to probe the hepatic free heme pool.

Subcutaneous administration of CoCl2, a well recognized inhibitor of hepatic heme synthesis, to rats results in the functional stimulation of total (holo- + apo) tryptophan 2,3 dioxygenase (TDO), a hemoprotein and the key rate-limiting enzyme in the oxidative metabolism of tryptophan to formylkynurenine. Because basal holo-TDO activity is not altered, TDO stimulation appears to be entirely due to CoCl2-mediated increase of its apoprotein. This apoTDO increase was blocked by conventional inhibitors of protein synthesis (actinomycin D, cycloheximide), thereby revealing that such CoCL2-mediated apoprotein increase truly reflected TDO induction. To determine whether the CoCl2-mediated TDO induction involved the action of its natural physiological inducers (glucocorticoids) or was due to direct CoCl2-regulation of the TDO gene, rats were adrenalectomized before CoCl2 administration. In adrenalectomized rats, CoCl2 failed to induce TDO, but induction was completely restored on administration of the glucocorticoid hydrocortisone, but not of adrenaline. These findings reveal that CoCl2-mediated TDO induction is indirect and entails glucocorticoid participation. In addition, because CoCl2 lowered the % heme saturation of TDO [= 100(holo TDO activity/total (apo+holo) TDO activity] largely by increasing the apoTDO protein levels rather than by affecting the basal holo-TDO levels (as expected from its inhibition of heme synthesis), these findings question the widely accepted use of the relative intrahepatic % heme saturation of TDO as a reporter of the hepatic "free" heme pool.

Adrenal Glands↗
PubMed1994

Clinical assessment of biplanar transesophageal echocardiography--a report of 125 cases.

One hundred and twenty-five patients with cardiovascular disease were examined by biplanar transesophageal echocardiography (BTEE), including 67 with rheumatic heart disease (7 monitored during operation), 22 with aortic diseases, 20 with congenital heart diseases, and 16 with other kinds of heart disease. The results showed that BTEE was not influenced by corpulent and pulmonary emphysema and was better than transthoracic echocardiography at imaging the interatrial septum, left atrium and left atrial appendage, thoracic aorta, and mitral artificial valve and at intraoperative monitoring. BTEE was also better than single-plane transesophageal echocardiography, because BTEE could be used to observe the heart and thoracic aorta in transverse and longitudinal planes, thus enlarging the transmission "window" as well as allowing the entire lesion to be imaged. This study suggests that BTEE will have good prospects in clinical application.

Adolescent↗
PubMed1994

Treatment of adolescent myopia by pressure plaster of semen impatientis on otoacupoints.

295 cases (424 eyes) of adolescent myopia were treated by pressure plaster of Semen Impatientis on otoacupoints with a cure rate of 44.3% and a total effective rate of 98.5%. 36 random cases (69 eyes) were compared with the same number of similar control cases. Findings were that the therapeutic effects of the pressure plaster group excelled significantly those of the control group.

Acupuncture Points↗
PubMed1994

[Effects of iontophoretic application of hydrogen ion on the spontaneous discharge of the nucleus paragigantocellularis lateralis neurons in brainstem slices in rats].

The effects of iontophoretic application of H- (acid NS) on the spontaneous discharge of nucleus paragigantocellularis lateralis (PGCL) neurons were studied in brainstem slice in rat with multibarrel microelectrode techniques. Most of the PGCL neurons tested (18/20, 90%) showed an excitatory response to H+ and the response was dose dependent, but none was inhibited. The results suggested that there were H+ sensitive cells in PGCL and these cells may be involved in central chemoreception.

Animals↗
PubMed1994

[Effects of L-glutamic acid and its antagonist on spontaneous discharge of nucleus paragigantocellularis lateralis neurons in brainstem slice in rat].

We studied the effects of iontophoretic application of L-glutamic acid (L-Glu) and its antagonist DL-2-amino-5-phosphonovaleric acid (AP5) on the spontaneous discharge of the nucleus paragiganto-cellularis lateralis (PGCL) neurons and the influence of AP5 on L-Glu effect in brainstem slice in rat with the multibarrel microelectrode techniques. One hundred and thirty six units with stable spontaneous discharge were recorded in 51 rat brain slices, their discharge pattern being primarily a repetitive one. Both L-Glu and AP5 showed three kinds of effect on the PGCL neuronal spontaneous discharge: excitatory, inhibitory and no-effect, with the percentage of 80.65%, 8.06%, 11.29% for L-Glu and 28.00%, 8.00%, 64.00% for AP5 of the neurons tested, respectively. The excitatory effect showed a dose-response relationship. AP5 could block partially the excitatory effect of L-Glu on most neurons tested (71.87%). The results indicated that the neurons in PGCL in rat brain slice in vitro principally showed a spontaneous discharge with a repetitive firing pattern, and suggested that at cellular level there existed endogenous excitatory amino acid as neurotransmitter in PGCL and the neurons there possessed EAA receptors of both N-methyl-D-aspartate (NMDA) and non-NMDA subtypes.

2-Amino-5-phosphonovalerate↗
PubMed1994

[Detection of messenger RNA coding for BNP precursor in rat brain by in situ hybridization].

Messenger RNA coding for BNP precursor has been detected and mapped in histological sections of rat brain by in situ hybridization using specific rat BNP DNA probes labelled with 32P. The results showed that areas of highest concentration of BNP gene expression were located in the hypothalamus and in the verge area of the thalamus. Successively decreased concentration could also be found in amydaloid nuclei, olfactory bulb, hippocampus and cerebral cortex. While practically no BNP gene expression could be found in cerebellum and medulla oblongata.

Animals↗
PubMed1994

[Binocular competitive mechanisms in the visual cortex in early developing kittens of monocular deprivation and reverse suture revealed by pattern visual evoked potential].

Using contrast reversing square- wave gratings as stimuli the pattern visual evoked potentials (P-VEP) and pattern electroretinograms (P-ERG) were simultaneously recorded to determine the spatial frequency tuning curves for kittens of monocular deprivation (from 8th to 12th postnatal week) and reverse suture (from 12th to 15th postnatal week), as compared with those of normal kittens of the same age and adult cats. The results showed that in the range from spatial frequency 0.12 to 1.5 c/d the amplitudes of P-VEP responses driven respectively by the left and the right eyes in normal kittens were similar but clearly smaller than those driven binocularly. For kittens with one eye deprived, the P-VEP amplitudes driven by the deprived eye decreased markedly. In contrast, the P-VEP amplitudes driven by the undeprived eye increased significantly, while the P-VEP amplitudes driven by simultaneous stimulation of both eyes were intermediate between the two monocular responses. For the reversely sutured kittens, the P-VEP amplitudes driven by the formally deprived eye recovered to some extent, while the P-VEP amplitudes driven by the reversely sutured eye decreased, and their amplitudes tended to be quite close. The P-VEP amplitude driven by both eyes was the biggest. Neither such shift of spatial frequency tuning curves of the P-VEP in adult cats, nor such functional competition between the two eye in P-ERG responses during early development of kittens of monocular deprivation and reverse suture was found.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

[New species of Haloarcula].

Three strains of pleomorphic halobacteria (A5, B2 and B-B2) were isolated from salt lakes of Xinjiang, China. Based on the Bergey's Manual of Systematic Bacteriology, Volume 3 (1989) and the analytical results of polar lipids, the three strains could be included in the genus Haloarcula. But since they differ from normally accepted two species of this genus in cell shape and physiological and biochemical features, it is suggested that the three strains belong to a new species, called Haloarcu la aidinensis sp. nov.

China↗
PubMed1994

High frequency of mutator phenotype in human prostatic adenocarcinoma.

Mutator phenotype of nucleotide repeats has been implicated to be involved in human cancer and other diseases. This type of instability may be the direct result of DNA replication and/or repair errors. To examine mutator phenotype during the development of human prostate cancer, we undertook this study to screen 57 patients with prostatic adenocarcinoma for possible mutator phenotype at 18 microsatellite marker loci on 12 chromosomes (3p, 5q, 6p, 7p, 8p, 10q, 11p, 13q, 16q, 17p, 18q and Xq). Overall, in 37 of 57 patients, we have found positive mutator phenotype in at least one of the loci analysed. A significantly greater number of cases were found to be positive for this phenotype among the poorly differentiated than the moderately- and well-differentiated prostatic adenocarcinomas. Our data suggest that mutator phenotype may play an important role in the development and progression of human prostate cancer.

Adenocarcinoma↗