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Biomedical subjects

C Li

Publications and source records attributed to C Li.

At least 1,153 records · Page 64Linked to original sources
PubMed1991

[Vitrectomy for nondiabetic vitreous hemorrhage].

Fifty cases (fifty-three eyes) of nondiabetic vitreous hemorrhage underwent vitrectomy. The visual acuity improved in 39 eyes (73.6%) postoperatively. Twenty seven eyes obtained a visual acuity of 0.05 or better. The postoperative vision was related to the etiology and macular function. Vitreous hemorrhage due to blunt trauma responded best. All of them had vision improved. Eales's disease also had a good result. 77% was improved in vision postoperatively. The main complications of surgery were recurrent vitreous hemorrhage and secondary glaucoma, especially hemolytic glaucoma (4/6). The timing for vitrectomy, degree of cutting and hemolytic glaucoma were briefly discussed.

Adolescent↗
PubMed1991

[Anti-oxidation of Paecilomyces Sinensis (S. Pnov.)].

This paper indicates that Paecilomyces sinensis ig 3g/kg/dx14 increases the amount of superoxide dismutase in the liver tissues of mice; that Paecilomyces sinensis is similar to natural Cordyceps sinensis in inhibiting the production of Lpo and increasing the amount of superoxide dismutase in the liver homogenates of mice in vitro. In addition Paecilomyces sinensis can also increase the amount of glutathione peroxidase in the liver homogenates of mice in vitro.

Animals↗
PubMed1991

[Anti-cholinesterase activity of fordine].

The inhibitory effect of fordine on human true cholinesterase (ChE) was found to be 55386 times larger than on pseudo ChE in vitro. There was a marked difference in the inhibition of fordine on pseudo ChE of different species. The order of the decrease of potency of fordine on true ChE of different species was man, dog, rabbit, cat, rat and mouse. The order of the decrease of potency on pseudo ChE was rabbit, rat, dog, cat, mouse and man. In vivo, it was shown that ChE in blood and brain was strongly inhibited by fordine, and the duration of the inhibitory action was comparatively long. The ChE activity inhibited by fordine may recover spontaneously.

Alkaloids↗
PubMed1991

[Effect of prefrontal cortex stimulation on the activity of pain-related neurons in parafascicular nucleus of thalamus in rats].

The effects of PFC stimulation on spontaneous and evoked discharges of neurons of parafascicular nucleus of thalamus were observed in rats. The results show that after PFC stimulation spontaneous of 78.7% PEN (48/61) and evoked discharges on noxious stimulation of 76.6% PEN (46/60) were decreased; spontaneous discharges of 72% PIN (18/25) were increased; inhibition response on noxious stimulation of 70.8% PIN (17/24) were decreased; and spontaneous discharges of 66.7% CON (6/9) and evoked discharges on noxious stimulation of 55.6% CON (5/9) were decreased. The results suggest that PFC might have analgesia action which was accomplished by modulating electric activities of pain-related neurons of parafascicular nucleus in thalamus.

Animals↗
PubMed1991

The antisense c-Ha-ras oligodeoxynucleotides inhibit the proliferation of the gastrocarcinoma-DNA-transformed rat 3-3 cells and reduce the p21 expression of the cells.

The Rat 3-3 is a secondary transformant of the rat fibroblast cell line (Rat-1) transfected with total DNA of a gastrocarcinoma cell line BGC-823. The cells over-express the c-Ha-ras oncogene which contains point mutation at the 12th codon. In order to determine how the activated c-Ha-ras oncogene expression governs the cell's transformation, two pentadecadeoxy-nucleotides AS-1 and AS-2 were synthesized. AS-1 was complementary to the single strand of the first three codons and the upstream sequence close to the ribosome binding site of c-Ha-ras mRNA. AS-2 was complementary to the 3' end of the first intron and the 5' end of the second exon of c-Ha-ras unripe RNA enclosed in the nucleus. The oligonucleotides could block either the translation of c-Ha-ras mRNA or the splicing of c-Ha-ras unripe RNA, thus inhibiting the expression of the activated c-Ha-ras oncogene and the proliferation of the transformed cells Rat 3-3. The inhibitory effect increased with a growing concentration of the antisense oligodeoxynucleotide (from 4-10 mumol/L) and reached its peak at 12 h after Rat 3-3 was treated with AS-1 and AS-2. This effect became weaker afterwards. The p21 level, product of c-Ha-ras, in the Rat 3-3, was examined by ELISA method. The result shows that the amount of p21 in the growth-inhibited cells is about 30% of that of the control cells.

Animals↗
PubMed1990

A 21S enzyme complex from HeLa cells that functions in simian virus 40 DNA replication in vitro.

A sedimentable complex of enzymes for DNA synthesis was partially purified from the combined low-salt nuclear extract-postmicrosomal supernatant solution of HeLa cell homogenates by poly(ethylene glycol) precipitation in the presence of 2 M KCl, discontinuous gradient centrifugation, Q-Sepharose chromatography, and velocity gradient centrifugation. In addition to the previously described 640-kDa multiprotein DNA polymerase alpha-primase complex [Vishwanatha et al. (1986) J. Biol. Chem. 261, 6619-6628], the enzyme complex also has associated topoisomerase I, DNA-dependent ATPase, RNase H, DNA ligase, a simian virus 40 origin recognition, dA/dT sequence binding protein [Malkas & Baril (1989) Proc. Natl. Acad. Sci. U.S.A. 86, 70-74], and proliferating cell nuclear antigen. Essentially all of the T antigen dependent simian virus 40 in vitro replication activity in the combined nuclear extract-postmicrosomal supernatant solution resides with the sedimentable complex of enzymes for DNA synthesis. Sedimentation analysis on a 10-35% glycerol gradient in the presence of 0.5 M KCl indicates that the enzyme complex is 21S. The associated enzymes for DNA synthesis and in vitro simian virus 40 replication activity cofractionate throughout the purification of the 21S complex. The DNA polymerase and in vitro simian virus 40 replication activities are both inhibited by monoclonal antibody (SJK 132-20) to human DNA polymerase alpha and by 5-10 microM butylphenyl-dGTP, indicating that the association of DNA polymerase alpha with the 21S enzyme complex is essential for the initiation of SV40 DNA replication in vitro.

Adenosine Triphosphatases↗
PubMed1990

Fluprazine hydrochloride: no influence on the odor detection performance of male rats.

Fluprazine hydrochloride (DU 27716) decreases copulatory and offensive attack behaviors of male rats and increases their latency to locate buried food in an open field. Since such behaviors are mediated to some degree by the olfactory system, several investigators have hypothesized that this drug may produce an overall impairment in olfactory sensitivity. To test this hypothesis, the influences of five doses of fluprazine hydrochloride (1.0, 2.5, 5.0, 7.5 and 10.0 mg/kg IP) on the odor detection performance of 12 adult male Long Evans rats was assessed, relative to saline, using high precision olfactometry and a go/no-go operant odor detection task. Treatments were administered every 3rd day in counterbalanced order, with the drug or saline injections occurring 30 minutes before the 260-trial test sessions. No significant influence of fluprazine was observed on odor detection performance, as measured by the nonparametric signal detection sensitivity index SI and the percentage of correct trials. These results indicate that fluprazine does not induce generalized olfactory impairment.

Animals↗
PubMed1990

Structure-property relationships for the design of polyiminocarbonates.

Structure-property relationships for the design of new polyiminocarbonates were established, based on the investigation of thermal stability and processibility, morphology, tensile strength, hydrolytic degradation and drug release profiles of 15 different polyiminocarbonates. The results indicated that some polyiminocarbonates were among the mechanically strongest, bioerodible polymers currently available. The iminocarbonate bond was highly unstable under physiological conditions, facilitating the design of rapidly degrading devices. The drug-release profiles of certain polyiminocarbonates exhibited lag periods, facilitating the design of pulsed-release or delayed-release devices. Possible limitations of the practical applicability of polyiminocarbonates as biomaterials were the low thermal stability of the iminocarbonate linkage and the complicated, two-phase degradation mechanism that led to the formation of slowly degrading residues of low molecular weight. To identify non-toxic diphenols as monomers for the synthesis of polyiminocarbonates, derivatives of tyrosine dipeptide were systematically explored. Using structure-property relationships as design guidelines, desaminotyrosyl-tyrosine hexyl ester was identified as a promising, tyrosine-derived diphenol. The corresponding poly(desaminotyrosyl-tyrosine hexyl ester iminocarbonate) formed amorphous, transparent films and was mouldable at about 70 degrees C. It had a tensile strength of 400 kg/cm2 and a tensile modulus of 16,300 kg/cm2. Under physiological conditions in vitro, a thin film made of high molecular weight poly(desaminotyrosyl-tyrosine hexyl ester iminocarbonate) degraded to low molecular weight oligomers within 5 d. The results indicated that polyiminocarbonates and in particular poly(desaminotyrosyl-tyrosine hexyl ester iminocarbonate) might be of interest in a variety of biomedical applications.

Animals↗
PubMed1990

Assignment of the human gene for CREB1 to chromosome 2q32.3-q34.

The nuclear phosphoprotein cAMP-response-element-binding-protein 1 (CREB1) is involved in the transcriptional regulation of cAMP-inducible genes. We have determined the chromosomal location of the human CREB1 gene by using a cDNA probe. Southern blot analysis of genomic DNA from a panel of mouse-human somatic cell hybrids indicated that the CREB1 gene resides on human chromosome 2. Analysis of a somatic cell hybrid containing a chromosome 2 translocation narrowed assignment of the CREB1 locus to the terminal third of chromosome 2. Finally, in situ hybridization allowed localization of the gene to the 2q32.3-q34 region. This knowledge may prove valuable in molecular analysis of translocations occurring in this region and in exploring the possibility of a role for the CREB1 locus in malignancy.

Animals↗
PubMed1990

Organogenesis in C. elegans: positioning of neurons and muscles in the egg-laying system.

One of the final stages in the development of egg-laying behavior in the nematode C. elegans is the organization of 8 motor neurons (2 HSN and 6 VC cells) and 8 muscles into a motor system to control the opening of the vulva. Using mutations that disrupt the development of specific components of the egg-laying system and laser microsurgery to ablate selected precursor cells, we have determined that the guidance of the egg-laying neurons and muscles, and in particular the VC neurons and vulval muscles, into the vulval region is dependent on interactions with surrounding epithelial and gonadal tissue and appears to be independent of neuron-neuron and neuron-muscle interactions. The development of the egg-laying system can be described as a series of cell interactions in which certain cells arise through induction and subsequently provide inductive cues themselves.

Animals↗
PubMed1990

Median nerve somatosensory evoked potentials and the Glasgow Coma Scale as predictors of outcome in comatose patients with head injuries.

Median nerve somatosensory evoked potential (SSEP) grades and Glasgow Coma Scale (GSC) scores were obtained from 51 patients with head injuries within 1 week after the injury to determine the relationship of these scores, both individually and combined, to outcome scores obtained more than 6 months after the injury. SSEP grading was based on the presence or absence of the cortical evoked potential, the amplitude of the early cortically generated P22 wave form, and the conduction time through the brain (P/N13-N20 interpeak latency). SSEP responses from both sides of the brain were combined and graded from 1 to 6. The GCS was graded without the verbal component (maximum score, 10), because all patients were intubated. All patients were unresponsive to commands. Median SSEP grades correlated better with Glasgow Outcome Scale and Barthel Index scores (R = 0.57 and 0.64, respectively; P less than 0.00001) than GCS scores did (R = 0.35 and 0.37, respectively, P less than 0.00001), and combining SSEP grades and GCS scores did not improve the predictive power of the model (R = 0.57 and 0.64, respectively; P less than 0.00001). All SSEP Grade 1 patients (n = 13) either died or remained in a vegetative state. In contrast, all SSEP Grade 6 patients (n = 7) had a moderate disability or good recovery. This study demonstrates the prognostic value of early quantitative median nerve SSEP grading for patients with head injuries who are unresponsive to commands within 1 week after the injury.

Analysis of Variance↗
PubMed1990

Adenovirus early region 3 promoter regulation by E1A/E1B is independent of alterations in DNA binding and gene activation of CREB/ATF and AP1.

Transcription of the adenovirus early region 3 promoter is strongly induced by the adenovirus E1A protein. Previous DNase I footprinting has indicated that four regions in this promoter serve as binding sites for HeLa nuclear proteins. These include binding sites for NF-1 (site IV), AP1 (site III), CREB/activating transcription factor (ATF) (site II), and TATA (site I). To determine the relative importance of these sites in both the in vivo and in vitro transcriptional regulation of the E3 promoter, oligonucleotide-directed mutagenesis of these sites was performed. Each of these constructs was assayed by transfection onto HeLa cells in the presence of either dl434, an E1A/E1B deletion mutant, or wild-type adenovirus. Mutations of either the ATF- or AP1-binding sites but not the TATA- and NF1-binding sites resulted in severe decreases in both basal and E1A/E1B-induced transcriptional levels. These constructs were also assayed in in vitro transcription assays with cellular extracts prepared from dl434-infected or wild-type-adenovirus-infected HeLa cells. The wild-type E3 promoter was transcribed approximately 30 times more efficiently in extracts containing the E1A/E1B proteins compared with extracts lacking these proteins. Mutations of either the TATA element, the ATF site, or the AP1-binding site decreased both basal and E1A/E1B-induced transcriptional levels. Gel retardation analysis using these extracts indicated that the binding to ATF, AP1, or NF1 oligonucleotides was not altered in the presence of the E1A/E1B proteins compared with extracts lacking these proteins. Northern (RNA) blot analysis of c-jun and CREB RNA prepared from wild-type adenovirus and dl434-infected cells indicated that the levels of these RNAs were not altered by the E1A/E1B proteins. Immunoprecipitation of AP1 and CREB from both dl434- and wild-type-adenovirus-infected cells indicated that the amounts of these proteins were not significantly altered. These results suggest that E1A/E1B-induced activation of the E3 promoter does not involve activation of transcription factor genes nor a change in the DNA binding activity of important promoter-binding components. Our results are consistent with a model in which the E1A/E1B proteins either directly or indirectly alter the interactions of factors that bind to the basal E3 promoter transcription complex, thereby inducing transcription.

Adenovirus Early Proteins↗
PubMed1990

CREB regulation of cellular cyclic AMP-responsive and adenovirus early promoters.

The cyclic AMP (cAMP) response element-binding protein (CREB) has been demonstrated to be a key mediator of cellular promoter response to cAMP. The binding site for this protein in many cellular cAMP inducible promoters (CRE) contains the palindrome sequence TGACGTCA, which contains two half-sites for CREB binding. A related promoter element, with the core sequence TGACG, has significant homology to an AP1-binding site and contains only one half-site for CREB binding. A group of factors known as activating transcription factors (ATF) have been found to bind to the latter and related sequences found upstream of early adenovirus promoters induced by E1A, and these factors are highly homologous to the CREB protein. We wished to characterize CREB, c-jun, and c-fos binding to these sites in the somatostatin gene (CRE) and in the adenovirus early region 3 promoter (E3/ATF). Oligonucleotides complementary to each of these sites were used in gel retardation assays with in vitro-translated CREB protein. These studies indicated that CREB bound primarily as a dimer to both a single and two half-sites, though there was increased affinity to the double compared with the single half-site. The c-jun and c-fos proteins also bound to both the somatostatin CRE- and E3/ATF-binding sites, but CREB did not bind to AP1 recognition sites nor was it capable of forming heterodimers with either c-jun or c-fos. Truncations of the CREB protein, which eliminated regions of the protein containing consensus sites for phosphorylation by protein kinase A, protein kinase C, and casein kinase II, bound to both the CRE and ATF sites, indicating that these consensus sites were not essential for DNA binding or dimer formation. Transfection of CREB and protein kinase A expression constructs into F9 cells with promoters containing either a single or two half-sites for CREB binding indicated that CREB was capable of similar levels of activation of these constructs. However, the fold activation by CREB was higher for constructs containing a single half-site compared with those containing two half-sites. These results demonstrate that multiple mechanisms may regulate CREB binding, including variations in the sequences in the promoter-binding site and the presence of related DNA-binding proteins.

Adenoviridae↗
PubMed1990

Pharmacokinetics of cefpiramide in rats acutely intoxicated with carbon tetrachloride.

Pharmacokinetics of cefpiramide (CPM) were investigated in normal rats and rats with hepatic intoxication induced by a single oral administration of carbon tetrachloride (CCl4). The elimination half-life of the antibiotic was prolonged in CCl4-intoxicated rats and the total body clearance in CCl4-intoxicated rats (153.9 ml/h/kg) was about 40% of the control value (390.3 ml/h/kg), while the volume of distribution for CPM was scarcely affected. The hepatic clearance of CPM was markedly diminished and the renal clearance of CPM was slightly, but not significantly, decreased in CCl4-intoxicated rats. It seems that the hepatic clearance of CPM was decreased owing to at least two factors; (1) decrease in CPM uptake by hepatocytes and (2) decrease in bile flow, while the renal clearance of CPM was slightly decreased owing to decrease in the renal tubular secretion. These results suggest that CCl4 intoxicates not only the liver but also the kidney to a small extent.

Animals↗
PubMed1990

Somatosensory evoked potentials and neurological grades as predictors of outcome in acute spinal cord injury.

An analysis of Motor Index score, pinprick sensory score, joint position sense score, somatosensory evoked potential (SSEP) grade in the ulnar (SSEPu) and posterior tibial (SSEPt) regions, and overall SSEP grade (mean SSEPu + t) was conducted in 36 patients with cervical spinal cord injuries to determine the relationship of these scores, both individually and in combination, to functional outcome (as determined using the Barthel Index) at 6 months after injury. The clinical and electrophysiological data were obtained on the same day within 2 weeks after injury. Nineteen patients underwent two SSEP tests 1 week apart within the first 3 weeks following injury in an attempt to identify mean SSEPu + t improvement. Somatosensory evoked potential grading was based on the presence or absence of the cortical evoked potential, the amplitude of the early cortically generated waveform (P22 or P37), and the interpeak latency across the lesion site. Mean SSEPu + t had the strongest individual relationship with outcome (R-square 0.75, p less than 0.0001) and mean SSEPu + t improvement over a 1-week interval during the first 3 weeks after injury was associated with Motor Index score improvement over a 6 month period. Joint position sense score was the best clinical predictor of outcome (R-square 0.64, p less than 0.0001). Mean SSEPu + t correlated with outcome more closely than the combination of Motor Index score and pinprick sensory score. Mean SSEPu + t in combination with all three clinical indicators produced the strongest correlation with outcome (R-square 0.87, p less than 0.0001). This study confirms the prognostic value of quantitative SSEP analysis for patients with acute spinal cord injuries.

Acute Disease↗