Biomedical subjects
Publications and source records attributed to L Liu.
Two kinds of Chinese mineral drug Limonitum (a special ore of Limonitum in egg type and a general ore of Limonitum) were identified. The results showed that the main chemical components and optical characters of the two drugs were similar, but there were considerable differences in properties, element contents and IR spectra.
OBJECTIVE: To observe the possibility of maternal-fetal vertical transmission of human papillomavirus (HPV) via amniotic fluid. SUBJECTS AND METHODS: Specimens of cervical secretions from 30 pregnant women were obtained during the third trimester before rupture of membrane, and specimens of pharyngeal secretions of their neonates were obtained 12-48 h after birth. Amniotic fluids were collected in 13 pregnant women during cesarean section. The presence of HPV types 6, 11, 16, 18, 31, 33, 35, 38 deoxyribonucleic acid were detected by consensus polymerase chain reaction. RESULTS: HPV deoxyribonucleic acid was found in 16 cervical secretions, 14 pharyngeal secretions and in 3 amniotic fluids, the positive rate was 53.3%, 46.7%, 23.1% respectively. The pharyngeal secretion was also HPV positive in one of the three neonates from the amniotic fluid positive mothers. CONCLUSION: The results indicate that HPV can be transmitted in utero through amniotic fluid and cesarean section can not protect the neonates against vertical transmission completely.
OBJECTIVE: To observe the changes of ocular anterior segment and the relation between the intraocular pressure (IOP) and these changes after the topical application of cycloplegia using ultrasound biomicroscope (UBM), especially to observe the changes of ciliary body thickness and ciliary body-lens distance. METHODS: The quantitative measurement of UBM and the measurement of IOP had been done in 48 normal eyes before and after the topical use of 2% homatropine solution. The results were statistically analyzed. RESULTS: In the parameter reflecting the change of the anterior chamber angle after using 2% homatropine, the trabecular iris angle decreased, the angle open distance 250 decreased, the iris thickness 1 increased, the anterior chamber became deeper and the iris-lens contact distance became shorter, and all these differences were statistically significant (P < 0.05). In the parameter reflecting the changes of ciliary body, the ciliary body thickness and the ciliary process thickness decreased, the scleral ciliary body angle increased, the iris-zonule distance decreased and the ciliary body-lens distance increased, and all these differences were significant statistically (P < 0.05). The IOP increased from 2.35 +/- 0.46 kPa to 2.43 +/- 0.47 kPa after the topical use of 2% homatropine, but the differences were not statistically significant (P > 0.05). CONCLUSIONS: After the topical application of cycloplegia, the anterior chamber becomes deeper, the anterior chamber angle becomes narrower, the ciliary body becomes thinner and moves backward and the ciliary body-lens distance increases. By using UBM the structure of ocular anterior segment in its moving state can be observed and these structures can be measured quantitatively. The ultrasound biomicroscopic imaging has its advantages in the morphological study of ocular anterior segment.
OBJECTIVE: To study the mechanism of malignant glaucoma using ultrasound biomicroscope (UBM) combined with general A scan and to observe the conditions of cilio-lens block in living eyes at the realtime when malignant glaucoma is occurring. METHODS: 31 eyes from 27 patients with malignant glaucoma were evaluated and 54 normal eyes and 72 eyes of primary angle-closure glaucoma were studied as the controls. RESULTS: Of the 31 eyes, close attachments between the ciliary body and the lens were found in 18 eyes (58.1%) and slits between them were found in 13 eyes (41.9%) during the onset of malignant glaucoma. Ciliary body thickness increased significantly (P < 0.05). Fluid in the supraciliary space was found in 11 eyes. CONCLUSIONS: The mechanism of malignant glaucoma is associated with the abnormal relationship among anterior vitreous, ciliary process and lens periphery. Fluid in the supraciliary space makes the ciliary process closer to the lens periphery. It is one of the factors causing cilio-lens block. The ultrasound biomicroscopic image is a new better practicable method to diagnose malignant glaucoma during its onset compared with other methods at present used in the clinical work. It is much more valuable to differentiate the pupillary block glaucoma from malignant glaucoma by using ultrasound biomicroscopy.
OBJECTIVE: To investigate the mechanism of primary angle closure glaucoma (PACG) especially the role of the changes of ciliary body using ultrasound biomicroscope (UBM) combined with general A scan. METHOD: 99 eyes with PACG, including 50 eyes with acute and 49 eyes with chronic PACG, were evaluated and 58 normal eyes were in the control group. RESULTS: Compared with the normal eyes the PACG eyes had their anatomic features. They had a smaller corneal diameter, shorter axial length, shallower anterior chamber, thicker lens, more relative anterior location of lens, swelling of ciliary process and anterior rotation of ciliary body. All these differences were significant statistically (P < 0.05). Compared with the chronic PACG eyes the acute PACG eyes had a shallower anterior chamber and a more anteriorly situated lens position. The differences were significant statistically (P < 0.01). Compared with the normal eyes the acute PACG eyes had a shorter ciliary body - lens distance and the difference was significant (P < 0.05); the chronic PACG eyes also had a shorter ciliary body-lens distance, but the difference was not significant (P > 0.05). CONCLUSIONS: The PACG eyes have their anatomic features. Among these factors the pupillary block caused by the anterior displacement of lens and the narrow angle induced consequently are the common mechanism. The swelling ciliary process, the positional changes of the ciliary body and age-related thicker lens are possibly the initial causes causing the forward movement of lens, and the pupillary block plays a more important role in the pathogenesis of acute PACG.
8 allele and group specificity at HLA-DRB1 locus were genotyped in 159 unrelated individuals of Liaoning Han, with polymerase chain reaction-sequence specific primers. The range of gene frequencies was from 0.02201-0.23899. Heterozagosity was 83%. 33 out of 36 theoretical genotypes were identified and the result conformed to Hardy-Weinberg equilibrium law. The present method can be used not only in paternity test, individual identification, but also in clinic graft matching between donor and recipient as well as the study of HLA.
Pathological changes due to intoxication of tetramethylenedisulphotetramine (TETS) were studied. The results showed that the signs of asphyxia were obvious, so were the congestion and edema of the brain. The spotty and focal hemorrhages in brain stems, multiple myolysis of papillary muscles and contractionbands necrosis of myocardium were observed occasionally. The main clinical symptom of intoxication was frequent clinic--tonic convulsions, which were similar to the grandma epilepsy. The poisoned died mainly in 3 hours. The general poisoning symptoms, LD50, toxicological mechanism and medicolegal expertise were also reviewed.
AIM: To construct an eukaryotic expression system pcDNA3/ESG-HeLa cell and explore the possibility of whether the eggshell protein might be used as potential targets for vaccine development. METHODS: The eggshell protein gene (ESG) was amplified using PCR technique and inserted into vector pcDNA3 to construct recombinant vector pcDNA3/ESG. The expression of the eggshell protein was performed in HeLa cell line. SDS-PAGE, dot-ELISA and Western blotting were used to identify the antigenicity of the expressed product. RESULTS: The amplification of ESG (618) bp was achieved and high level expression of the eggshell protein was obtained in HeLa cells and the amount of total expressed products was up to 24.4%. Dot-ELISA and Western blot analysis demonstrated that the expressed protein could be recognized by sera from rabbits infected with S. japonicum and from female worm- or egg-immunized rabbits. In addition, the expressed protein could specifically stimulate proliferative response of the immunized BALB/c mouse spleen cells, the transformation rate being up to 44.57%. CONCLUSION: The eukaryotic expression system pcDNA3/ESG was successfully established and high level expression of the eggshell protein of S. japonicum was achieved in HeLa cell line. The expressed recombinant protein exhibited immunological activities.
The rates of demineralization of 5 organic acids (mathanoic acid, formic acid, propionic acid, Lactic acid, acetic acid, mixed acid) to the bovine enamel were tested and analysed with the self-made calcium ionselective microelectrodes(Ca(2+)-ISME) basing on a neutral carriers of ETH1001. The results showed; 1. The difference between the rates of demineralization of formic acid and lactic acid, formic acid and propionic acid, formic acid and acetic acid, acetic acid and mixed acid, acetic acid and lactic acid, propionic acid and mixed acid, propionic acid and lactic acid, lactic acid and mixed acid were of great significance (P < 0.01); 2. The rates of demineralization of acetic and mixed acid decreased with time, due to saturation of the solution during demineralization; 3. Ca(2+)-ISME was of the advantages of simplicity, rapidity, sensitivity and accuracy. The results suggest that the cariogenic potential is related to different acid products of different cariogenic bacteria, and the degree of mineral saturation within solution affects the rate of demineralization.
To study the relation of neonatal hyaline membrane disease (HMD) and congenital human cytomegalovirus (HCMV) infection, two pairs of primers were synthesized according to the sequence of HCMV conserved region of the immediate--early(IE) gene. The nested polymerase chain reaction (nested-PCR) was used for the detection of HCMV-DNA of the paraffin-embedded lung tissues from neonatal HMD and non-neonatal HMD. 11 of 30 neonatal HMD patients were positive, the positive rate was 36.7%. Specimens of non-neonatal HMD patients were all negative. The difference between the two groups was significant (chi 2 = 5.05, P < 0.025). There is close relationship between neonatal HMD and congenital HCMV infection.
Alkyltransferase (AGT) repairs alkylation at O6-guanine in DNA and is a major determinant of susceptibility to alkylating chemotherapeutic agents and carcinogens. Using a newly developed flow cytometry assay with the monoclonal anti-AGT antibody, mT3.1, we compared AGT expression in single-cell suspensions with standard biochemical and Western blot assays to validate the fluorescence-activated cell sorting (FACS) method and develop potential applications. From Chinese hamster ovary cells (CHO) transfected with human O6-methylguanine-DNA methyl-transferase cDNA, 6 CHO-O6-methylguanine-DNA methyl-transferase clones were isolated that expressed 0.3 to 64 fmol/microgram DNA (by biochemical assay) of human AGT. FACS yielded a linear relationship between mean fluorescence intensity and both AGT activity by biochemical assay and AGT protein by Western blot. Using this standard curve, FACS-analyzed AGT protein content in human peripheral blood mononuclear cells (PBMCs) from normal donors ranged from 6.1 to 12.8 fmol/microgram DNA, similar to those obtained by biochemical assay and Western blot. This suggests that the level of immunoreactive protein appears to be an accurate predictor of AGT activity in the steady state. FACS-AGT in PBMCs from normal donors had a low index of heterogeneity within the sample. In contrast, by FACS-AGT analysis of human bone marrow samples and granulocyte-colony-stimulating factor-mobilized PBMCs, AGT was lower and had an 8-fold higher index of heterogeneity than observed in PBMCs from normal donors. After treatment with O6-benzylguanine (O6-bG), Western and FACS-AGT detected significant levels of AGT protein for up to 24 h, whereas biochemical assay showed AGT activity less than 5% of the basal level. Because only the biochemical assay accurately measures net AGT activity, the AGT-FACS assay will not be useful in clinical trials to assess the efficacy of O6-bG or other AGT inhibitors. Thus, AGT-FACS can rapidly assess the heterogeneity of steady-state AGT in single-cell suspensions and may be useful for assay in lymphocytes, bone marrow cells, leukemic myeloma plasma cells, or cells transfected with the AGT gene; Western blot analysis is better for small samples such as tumor biopsies, whereas biochemical assay is best able to measure enzyme activity and its inactivation by O6-bG or other agents.
PURPOSE: In a previous study, an increase in Na,K-ATPase alpha 2 expression was detected in the epithelium of porcine lenses exposed to amphotericin B, an ionophore that also increases lens sodium and stimulates active sodium transport. The purpose of the present study was to determine whether an increase of Na,K-ATPase alpha 2 synthesis is a response to an episode of rapid Na-K transport or whether the increase in lens sodium alone can initiate the response. METHODS: Western blot analyses were conducted to probe for Na,K-ATPase alpha polypeptides in membrane material isolated from porcine lens epithelium. Ouabain-sensitive adenosine triphosphate hydrolysis was used as an index of Na,K-ATPase activity, and lens ion content was determined by atomic absorption spectrophotometry. 86-Rubidium (86Rb) uptake was measured as an indicator for active potassium transport. RESULTS: 86Rb uptake was markedly diminished in lenses exposed to dihydro-ouabain (DHO), signifying inhibition of active sodium-potassium transport. Consistent with this, the sodium content of DHO-treated lenses increased. By western blot analysis, a marked increase of Na,K-ATPase alpha 2 polypeptide could be detected in the epithelium of DHO-treated lenses. To rule out the possibility that apparent stimulation of Na,K-ATPase alpha 2 synthesis stemmed from binding of DHO to Na,K-ATPase sites, experiments were conducted to confirm an increase of Na,K-ATPase alpha 2 polypeptide in the epithelium of lenses exposed to low-potassium medium to inhibit active sodium-potassium transport. Consistent with the apparent increase of Na,K-ATPase polypeptide, Na,K-ATPase activity was detectably increased in epithelial material isolated from lenses pretreated with DHO or low-potassium medium. CONCLUSIONS: An increase in Na,K-ATPase alpha 2 polypeptide can occur in the epithelium of lenses subjected to an episode of sodium pump inhibition. This suggests the response could be triggered by an increase in cell sodium and does not necessarily require a period of stimulated active sodium-potassium transport.
An epidermal growth factor (EGF)-dextran-boron conjugate for targeting against EGF receptor-rich tumours was investigated regarding uptake and distribution in vivo. EGF served as the tumour-seeking part and dextran was the carrier for the potentially toxic boron. Nude mice carrying subcutaneous tumours on the flanks were injected with conjugate either i.v. or intratumorally. The xenografts were from Chinese hamster ovary cells transfected with the gene for the human EGF-receptor (CHO-EGFR), and these cells expressed the EGFR. Non-transfected cells without EGF-receptors (CHO) were used as controls. No accumulations in tumours could be observed following the i.v. injections but there were, in both tumour types, high accumulations in the liver. Following intratumoral injections the accumulations were higher in the CHO-EGFR tumours than in the CHO tumours. The tumour over blood and liver ratios were also higher for the CHO-EGFR tumours than for the CHO tumours. Thyroid accumulations after the intratumoral injections indicate different degradation patterns of the conjugate in CHO-EGFR animals than in CHO animals. In conclusion, after intratumoral injections the conjugate showed receptor-dependent binding to EGFR-rich tumours, and the tumour-to-blood and tumour-to-liver ratios were promising.
We have examined the glial cell response, the possible expression of compounds associated with the complement cascade, including the putative complement inhibitor clusterin, and their cellular association during Wallerian degeneration in the central nervous system. Examination of the proliferation pattern revealed an overall greater mitotic activity after rhizotomy, an exclusive involvement of microglia in this proliferation after peripheral nerve injury, but, in addition, a small fraction of proliferating astrocytes after rhizotomy. Immunostaining with the phagocytic cell marker ED1 gradually became very prominent after rhizotomy, possibly reflecting a response to the extensive nerve fiber disintegration. Lumbar dorsal rhizotomy did not induce endogenous immunoglobulin G (IgG) deposition or complement expression in the spinal cord dorsal horn, dorsal funiculus, or gracile nucleus. This is in marked contrast to the situation after peripheral nerve injury, which appears to activate the entire complement cascade in the vicinity of the central sensory processes. Clusterin, a multifunctional protein with complement inhibitory effects, was markedly upregulated in the dorsal funiculus in astrocytes. In addition, there was an intense induction of clusterin expression in the degenerating white matter in oligodendrocytes, possibly reflecting a degeneration process in these cells. The findings suggest that 1) complement expression by microglial cells is intimately associated with IgG deposition; 2) axotomized neuronal perikarya, but not degenerating central fibers, undergo changes which induce such deposition; and 3) clusterin is not related to complement expression following neuronal injury but participates in regulating the state of oligodendrocytes during Wallerian degeneration.
We have identified a highly polymorphic pentanucleotide repeat (CCTTT)n within the 5'-putative promoter region of the human inducible nitric oxide synthase gene (iNOS, NOS2). Using a pair of specific primers derived from the human iNOS gene, we have also amplified this iNOS repeat in DNA from the following species: chimpanzee, gorilla, orangutan and macaque. As is found in man, both chimpanzees and gorillas are polymorphic at this locus. In contrast, the locus is monomorphic in macaques and orangutans. While the average number of repeats is similar in gorilla and man, there are considerably fewer repeats in chimpanzees. A comparison of the sequences flanking the (CCTTT)n repeats among these closely related species demonstrates the presence of long stretches of homopurine-homopyrimidine residues. Similar polypurine/polypyrimidine stretches have been identified in the promoter regions of a number of other vertebrate genes where they have been associated with transcriptional regulation, although a role for the (CCTTT)n repeat array in the human iNOS gene has not yet been demonstrated.
PURPOSE: Apoptosis is implicated in the death of retinal cells during both retinal differentiation and degeneration. We sought to investigate potential diffusible retinal cell signalling factors which may be responsible for this phenomenon. METHODS: 72 hr conditioned medium was collected from death-induced R28 retinal cells undergoing serum-starvation. This conditioned medium was filtered, titrated and added to fresh cultures of R28 cells for 24 hr. Cell death was measured by trypan blue exclusion; apoptosis was evaluated by TUNEL-in situ, DNA gel electrophoresis, and observations of cell morphology. RESULTS: Apoptotic cell death was at least two-fold greater in retinal cultures which received death-induced cell-conditioned medium. This apoptotic activity in conditioned medium did not appear to be due to nutrient-depletion of the medium, as the control situation (72 hr conditioned medium from resistant, non-dying cells) did not produce the same effect. This diffusible apoptotic activity was heat-labile (56 degrees C for 45 min). CONCLUSIONS: We have shown for the first time, in our system, that death-induced retinal cells release a diffusible, heat-labile apoptosis-promoting element. Further investigation will be necessary to determine whether this trigger of apoptosis is a toxic metabolite or an "apoptosis-promoting factor".
X-ray crystal structures of binary complexes of dUMP or dCMP with the Lactobacillus caseiTS mutant N229D, a dCMP methylase, revealed that there is a steric clash between the 4-NH2 of dCMP and His 199, a residue which normally H-bonds to the 4-O of dUMP but is not essential for activity. As a result, the cytosine moiety of dCMP is displaced from the active site and the catalytic thiol is moved from the C6 of the substrate about 0.5 A further than in the wild-type TS-dUMP complex. We reasoned that combining the N229D mutation with mutations at residue 199 which did not impinge on the 4-NH2 of dCMP should correct the displacements and further favor methylation of dCMP. We therefore prepared several TS N229D mutants and characterized their steady state kinetic parameters. TS H199A/N229D showed a 10(11) change in specificity for methylation of dCMP versus dUMP. The structures of TS H199A/N229D in complex with dCMP and dUMP confirmed that the position and orientation of bound dCMP closely approaches that of dUMP in wild-type TS, whereas dUMP was displaced from the optimal catalytic binding site.
LMX1 is a LIM-homeodomain (LIM-HD)-containing protein expressed selectively in insulin-producing beta-cell lines, and it it has been shown to activate insulin gene transcription. The human LMX1 gene was mapped by fluorescence in situ hybridization to chromosome region 1q22-q23, yet Church et al. (1994, Nat. Genet. 6: 98-105) identified two exon-trapping products from human chromosome 9 that were highly homologous to hamster LMX1. In the current study, we demonstrate tissue-specific expression of an LMX1 (now known as LMX1.1)-related gene, named LMX1.2. The chicken C-LMX1 gene, recently cloned using the hamster LMX1.1 sequence and shown to specify dorsal cell fate during vertebrate limb development (9), is actually more related to human LMX1.2 than LMX1.1. We have identified a unique simple sequence repeat polymorphic marker (hLMX1.2CA1) in a P1 genomic clone containing the human LMX1.2 gene and genetically mapped the marker on chromosome 9 between markers D9S1825 and D9S290 with odds of at least 1000:1. In addition, we localized the human LMX1.1 gene to three CEPH "B" yeast artificial chromosome clones (907A11, 935B12, and 947B2), along with two nearby polymorphic markers (D1S426 and D1S194)). Identification of this new LIM-HD-related gene may provide the opportunity to elucidate further the function of LIM class homeobox genes. Nearby polymorphic markers will be useful in testing the hypothesis that mutations in these LIM-HD genes result in genetic diseases such as non-insulin-dependent diabetes mellitus.