Biomedical subjects

J Liang

Publications and source records attributed to J Liang.

At least 91 records · Page 5Linked to original sources

PubMed2000

Socioeconomic gradient in old age mortality in Wuhan, China.

OBJECTIVES: The vast majority of studies on socioeconomic status (SES) and old age mortality are based on data derived from developed nations. This research examined the SES differentials in old age mortality in China, a developing nation. METHODS: Hazard rate models in conjunction with ordinary least squares and logistic regression analyses were used to ascertain the gross, direct, indirect, and interaction effects of SES on mortality during a 3-year period in a probability sample of 2,943 persons aged 60 years or older in Wuhan, China. RESULTS: Education, household economic well being, and urban-rural residence showed statistically significant gross effects on old age mortality. Education influenced mortality directly and indirectly. Household economic well being and urbanicity exerted indirect effects on mortality through mediating variables such as stress, social relations, and baseline health status. The mechanism through which education affected mortality differed between men and women, but SES differentials in mortality did not interact with age. DISCUSSION: SES differentials in old age mortality may be extended to a developing nation such as China. The observed gender by SES interaction effect on old age mortality has important implications for intervention. In particular. improving education among women in underdeveloped areas must remain a high priority, for policy makers in efforts to extend the life expectancy of women.

Activities of Daily Living↗

PubMed2000

Selective denervation and resection of cervical muscles in the treatment of spasmodic torticollis: long-term follow-up results in 207 cases.

OBJECT: To report the outcome of patients with selective denervation and resection of cervical muscles for spasmodic torticollis. METHODS: We reviewed 362 cases of surgically treated spasmodic torticollis. 207 patients were followed from 2 years to 29 years. RESULTS: Total or marked relief of symptoms with preservation of normal of nearly normal movements has been obtained in 87.9%. CONCLUSION: This procedure may be recommended if one to two years of conservative therapy does not offer satisfactory relief of symptoms.

Adolescent↗

PubMed2000

Angiostatin K(1-3) gene for treatment of human gliomas: an experimental study.

OBJECTIVE: To discuss the feasibility of gene therapy of human glioma by antiangiogenesis method. METHODS: Angiostatin K(1-3) cDNA with secretive signal was inserted into the polylinker sites of eukaryotic expression vector pcDNA3 to construct pcDNA-SAK(1-3). The vector was transfected into human SHG44 glioma cells by lipofectamine and the positive clone was screened by G418. The biological characteristics of glioma cells were examined by electronmicroscope and flow cytometry. The activity of angiostatin K(1-3) protein expressed by SHG44 cells was examined by the bovine micrangium endotheliocyte inhibition assay and immunofluorescence assay. When SHG44 cells were implanted into the strata subcutaneum of nude mice, tumor necrosis and micrangium were calculated immunohistochemically and electronmicroscopically for determining their characteristics and validity in gene therapy of human glioma by antiangiogenesis method. RESULTS: The eukaryotic expression vector pcDNA-SAK (1-3) was successfully constructed and transfected into glioma cells. The cells expressed angiostatin K(1-3) protein, and their tumorigenesis and angiogenesis in nude mice were greatly reduced. CONCLUSION: Angiostatin K(1-3) gene is feasible to treat human glioma. This experiment lays a foundation for gene therapy of the other solid tumors by antiangiogenesis method.

Angiostatins↗

PubMed2000

[Testing for isometry during reconstruction of the posterior cruciate ligament].

OBJECTIVE: To measure the isometric point of the attachment site in femur during the reconstruction of posterior cruciate ligament (PCL). METHODS: Seven fresh knee specimens from cadavers were adopted in this experiment. The anterior, posterior, proximal, distal and central points of the PCL's femoral attachment site were respectively anchored to the middle of the PCL's tibial attachment site by the trial isometer wires. The length changes of the intra-articular part of the wires were recorded while the knee was flexed from 0 degree to 120 degrees by a continuous passive motion(CPM) machine. RESULTS: The maximal length changes in every points were compared. It showed that the length change in anterior point was the biggest, the distal point was less than that of anterior point, and the proximal point was the least. There was significant difference between proximal and posterior points, but no significant difference between proximal and central points, neither between central and posterior points. All of the maximal length changes of proximal, central and posterior points were not greater than 2 mm. CONCLUSION: The femoral tunnel for the PCL reconstruction should be located at the proximal point, which is the middle point of upper edge of femoral attachment site. The selected point for femoral tunnel also may be moved slightly in the direction to central or posterior points according to the needs of operation.

Adult↗

PubMed2000

[A descriptive epidemiological investigation of anophthalmos and microphthalmos in China during 1988 - 1992].

OBJECTIVE: To investigate the descriptive epidemiological characteristics of cases with anophthalmos and microphthalmos in China. METHOD: According to the hospital-bases monitoring method, the birth defects monitoring program was undertaken in 443 - 588 hospitals from 30 provinces, cities and autonomous regions in China. Data of the new born babies including intra-uterine death and stillbirth from 28 weeks of gestation to a period of 7 days after birth were collected between 1988 and 1992. RESULTS: There were 3,246,408 babies monitored, among which 382 cases of anophthalmos and microphthalmos were found. The average prevalence rate was 1.18/10,000 in China. The decreasing tendency of prevalence rate was shown during the period (chi(2) = 7.381, P < 0.01). The average prevalence rate in the rural area was significantly higher than that in the urban area, and the female cases were higher than that of male cases. The prevalence rates among various regions varied from 0.21 to 2.29/10,000 with the highest in Gansu province and lowest in Tianjin city. 87.7% of the cases with anophthalmos and microphthalmos were associated with other congenital malformations (multiple malformations). The associated malformations were mostly facial (including ear, neck, etc.) followed by skeletomuscular system and central nervous system. 8.1% of cases were diagnosed as syndromes, among which trisomy 21 was the most common condition. CONCLUSIONS: There were large variations in the prevalence rates of anophthalmos and microphthalmos in different parts in China. Careful analysis, particularly the chromosome analysis, should be performed to correctly diagnose the cases, especially for those with multiple malformations.

Abnormalities, Multiple↗

PubMed2000

[Analysis on 2158 neural tube defects diagnosed prenatally by ultrasound examination].

A retrospective survey was made to study the prenatal diagnosis on neural tube defects(NTD) by ultrasound examination from 1990 to 1993 in China. A total of 2158 livebirths and stillbirths affected by NTD with 28 weeks or more of gestation were investigated in 233 hospitals of 28 provinces, municipalities and autonomous regions all over the country. The results showed that 61.8% of the NTD were diagnosed prenatally, and 56.5% of the NTD were diagnosed by ultrasound examination. The ratios of anencephaly, myelocele and meningocele diagnosed prenatally by ultrasound examination were 66.7%, 62.5% and 52.5% respectively. Thoracic(46.4%) and lumbar (43.4%) spina bifida were diagnosed more frequently than cervical(35.5%) and sacral(31.7%) spina bifida. The ratios of prenatal diagnosis on NTD by ultrasound examination in provincial, municipal, county, and factory hospital units were 55.7%, 59.4%, 49.0% and 57.2% respectively. The ratios of prenatal diagnosis of NTD by ultrasound examination from 1990 to 1993 were 53.5%, 55.8%, 60.7% and 54.7% respectively. There was an increase in the prenatal diagnosis of NTD by ultrasound examination from 1990 to 1993. The ratios of prenatal diagnosis of NTD in county hospitals by ultrasound examination were relatively low. Anencephaly, myelocele and meningocele were more frequently diagnosed by prenatal ultrasound examination.

Adult↗

PubMed2000

[Survey of the patients with oblique facial clefts in China].

OBJECTIVE: A descriptive study was conducted to investigate the epidemiological characteristics of oblique facial clefts in China. METHODS: From 1987 to 1992, data were collected from more than 500 hospital-based units involved in a monitoring program and were analyzed by the National Center for Birth Defects Monitoring. The monitored subjects were the hospitalized births from 28 weeks gestation to a period within 7 days after delivery. RESULTS: There were 71 cases of oblique facial clefts in 4,489,692 births with an incidence of 0.16/10(4) in China. The incidence of oblique facial clefts in the rural and urban areas were 0.19/10(4) and 0.14/10(4) respectively, 0.18/10(4) in males and 0.12/10(4) in females. No significant differences were found. The unilateral oblique facial clefts were counted for 80%, and bilateral cases 20%. The incidence of unilateral oblique facial clefts in males is higher than that in females. The perinatal mortality was as high as 51%. There are 76% cases with associated abnormalities, most of which involved the maxillofacial region. The most common associated abnormality is cleft lip with cleft palate. CONCLUSION: The incidence of oblique facial clefts in China is the same as those in other countries. There is an unilateral predominance in this defect, especially in males. The perinatal mortality of this defect is high.

China↗

PubMed2000

[Nonsyndromic cleft lip with or without cleft palate in Chinese population: analysis of 3766 cases].

A retrospective study was conducted to evaluate the variation trend in the incidence and epidemiological characteristics of nonsyndromic cleft lip with or without cleft palate in Chinese population. From 1988 to 1992, data were collected from more than 500 hospital-based units involved in a monitoring program and were analyzed by the National Center for Birth Defects Monitoring. The monitored subjects were the hospitalized births from 28 weeks gestation to a period within 7 days after delivery, which included 3246 408 perinatals and 3766 cases. The total incidence of nonsyndromic cleft lip with or without cleft palate was 11.6/10,000; the total incidence of celft lip alone was 3.8/10,000 and that of cleft lip with cleft palate was 7.8/10,000; no significant variation was noted in the annual incidence from 1988 to 1992. The incidence in males was 13.3/10,000, and 9.5/10,000 in females; there was a significant difference (P < 0.01). Of all the 3766 cases, cleft lip with cleft palate accounted for 67%, unilateral cleft lip 28% and unilateral cleft lip with cleft palate 43%. Left cleft lip and left cleft lip with cleft palate constituted 21% and 29% respectively. The sex-ratio was 1.6:1 for nonsyndromic cleft lip with or without cleft palate. It could be concluded that the incidence of nonsyndromic cleft lip with or without cleft palate showed no variation trend in China. Although no difference was found between urban and rural areas, the susceptibility to the defect was higher in males than in females. Cleft lip with cleft palate was more common than other types. There was a predominance of unilateral defects, of which most were on the left side.

China↗

PubMed2000

[The clinical application of different brightness and different saturation D-15 tests].

PURPOSE: To compare the clinical application of different brightness and different saturation D-15 tests. METHODS: Eighteen normal subjects (30 eyes), 19 cases (38 eyes) of congenital color vision defects and 36 cases (59 eyes) of eye diseases were tested with Panel D-15 test, Hann's double D-15 test, middle and low saturation CAS-PI (Psychological Institute, Chinese Academy of Sciences) D-15 tests. RESULTS: A few of the normal eyes made minor errors in the low saturation D-15 tests. All of the protanopes and deuteranopes could be detected correctly. Protanomalias and deuteranomalias showed normal arrange or some type of abnormal arranges in all of the 5 sets of D-15 tests. In sick eyes, the abnormal rates were the highest in the low saturation D-15 tests and the lowest in Panel D-15 test. CONCLUSION: The five sets of different brightness and different saturation D-15 tests had similar efficiencies of detecting congenital color vision defects. The abnormal rates of CAS-PI(4/5)D-15 tests and the CAS-PI(2/5)D-15 tests were similar to those of Panel D-15 test and Hann's Double D-15 test. Both tests can be used in the clinical setting.

Adolescent↗

PubMed2000

[An epidemiological investigation of anotia and microtia in China during 1988-1992].

OBJECTIVE: To investigate the epidemiological characteristics of cases with anotia and microtia in China. METHOD: The birth defect monitoring program was undertaken by a hospital-based monitoring method in 443-588 hospitals from 30 provinces, cities and autonomous regions across China. Data including intrauterine death and stillbirth from 28 weeks of gestation to a period of 7 days postpartum were collected between 1988 and 1992. RESULTS: A total of 3,246,408 births was monitored from 1988 to 1992, in which 453 cases had anotia and microtia. The average incidence was 1.40 per 10,000 during the five-year period. The decreased tendency of incidence was noted during the period (chi 2 = 5.5588, P < 0.05). The incidence in the urban area was significantly higher than that in the rural area. There was no sex difference in the incidence of anotia and microtia. The incidence varied among 30 provinces with highest incidence in Xinjiang province (2.08 per 10,000 births) and lowest in the Inner Mongolia Autonomous Region (0.33 per 10,000 births). In cases with the defects of anotia and microtia, 60.4% were accompanied with other congenital malformations. The proportion of multiple malformations with microtia and anotia was significantly higher than that of isolated case (chi 2 = 36.9277, P < 0.01). The highest incidence of concurrent malformations was anophthalmia or microphthalmia (13.1%), followed by facial cleft (12.6%), neural tube defects (10.0%), limb reduction defects (9.6%) and polydactyly (5.4%). There were also 3.5% cardiac defects. CONCLUSIONS: The prevalence of anotia and microtia varied among provinces across China. The high proportions of cases with anotia and microtia had multiple malformations. Therefore, careful examination of other malformations in patients with anotia and microtia is necessary.

Abnormalities, Multiple↗

PubMed1999

Neutrophil elastase and oxygen radicals enhance monocyte chemoattractant protein- expression after ischemia/reperfusion in rat liver.

BACKGROUND: The monocyte chemoattractant protein-1 (MCP-1) is produced during reperfusion injury and induces tissue factor that is the initiator of the clotting cascade. Neutrophil elastase is a crucial mediator of inflammatory tissue damage. Activation of the coagulation system stimulates cytokine production by activated leukocytes. We investigated the effects of neutrophil elastase and oxygen radicals generated by hypoxia associated with microthrombus formation on MCP-1 expression after ischemia/reperfusion in rat liver. METHODS: In vitro MCP-1 production by macrophages after stimulation with human neutrophil elastase (HNE) or oxygen radicals generated by hypoxanthine and xanthine oxidase was examined. Liver ischemia was induced in rats by occluding the portal vein for 30 min. An inhibitor of human neutrophil elastase (ONO-5046*Na, 10 mg/kg) and antithrombin III (AT-III, 250 U/kg) were injected i.v. 5 min before vascular clamping. Serum concentrations of MCP-1 were measured by enzyme-linked immunosorbent assay. RESULTS: Human neutrophil elastase or oxygen radicals significantly enhanced in vitro MCP-1 production by macrophage. Serum MCP-1 concentrations reached a peak at 6 hr after reperfusion and then gradually decreased. However, pretreatment of animals with AT-III or ONO-5046*Na alone resulted in significantly smaller increases in serum concentrations of MCP-1 after reperfusion. Pretreatment with both ONO-5046*Na and AT-III produced additive effects. The combined treatment with ONO-5046*Na and AT-III significantly reduced MCP-1 mRNA in liver after ischemia/reperfusion. CONCLUSIONS: MCP-1 production by macrophages is stimulated by neutrophil elastase and oxygen radicals generated by hypoxia, probably due to microthrombus formation after ischemia/reperfusion of the rat liver.

Animals↗

PubMed1999

Contextual effects of transforming growth factor beta on the tumorigenicity of human colon carcinoma cells.

Transforming growth factor betas (TGF-betas) are a growth factor family with negative autocrine growth functions for most epithelial cells including colon carcinoma cell lines. Both type I (RI) and type II (RII) transmembrane TGF-beta receptors have been shown to be indispensable for TGF-beta-mediated cell growth regulation. Previous studies using different model systems have shown that both overexpression of TGF-beta1 and transfection of antisense TGF-beta1 to reduce TGF-beta1 expression could lead to increased tumorigenicity. These results are seemingly contradictory and suggest that effects of TGF-beta modulation on malignant properties of cancer cells may be contextual. This study addresses this issue using human colon carcinoma cells (CBS and FET) to determine the effects of modulation of the various components of the TGF-beta system on in vitro and in vivo growth properties in two independent isogenic models of colon carcinoma. Cells were stably transfected with a tetracycline-repressible RII expression vector (CBS4-RII), a tetracycline-repressible expression vector containing a truncated RII cDNA lacking the serine/threonine kinase domain (CBS4-deltaRII and FET6-deltaRII), or with a vector containing the TGF-beta1 cDNA (CBS4-beta1S and FET-beta1S). Expression of the truncated RII reduced TGF-beta sensitivity, whereas overexpression of RII increased TGF-beta sensitivity. TGF-beta overexpression did not affect TGF-beta response. In vivo tumorigenicity assays revealed that CBS4-RII cells had lower tumorigenicity than control cells, whereas CBS4-deltaRII and CBS4-beta1S had higher tumorigenicity than controls. The CBS4 cells are poorly tumorigenic in athymic mice, and the wild-type FET6 cells are nontumorigenic. FET6-deltaRII cells formed rapidly growing tumors, and FET-beta1S cells also formed tumors. These data illustrate the paradoxical tumor-promoting and -suppressing effects of TGF-beta signaling activity in two isogenic model systems from human colon carcinomas, thus demonstrating that the effects of modulation of TGF-beta expression or TGF-beta signaling capability affects malignancy in a contextual manner.

Animals↗

PubMed1999

Chloride binding regulates the Schiff base pK in gecko P521 cone-type visual pigment.

The binding of chloride is known to shift the absorption spectrum of most long-wavelength-absorbing cone-type visual pigments roughly 30 nm to the red. We determined that the chloride binding constant for this color shift in the gecko P521 visual pigment is 0.4 mM at pH 6.0. We found an additional effect of chloride on the P521 pigment: the apparent pKa of the Schiff base in P521 is greatly increased as the chloride concentration is increased. The apparent Schiff base pKa shifts from 8.4 for the chloride-free form to >10.4 for the chloride-bound form. We show that this shift is due to chloride binding to the pigment, not to the screening of the membrane surface charges by chloride ions. We also found that at high pH, the absorption maximum of the chloride-free pigment shifts from 495 to 475 nm. We suggest that the chloride-dependent shift of the apparent Schiff base pKa is due to the deprotonation of a residue in the chloride binding site with a pKa of ca. 8.5, roughly that of the Schiff base in the absence of chloride. The deprotonation of this site results in the formation of the 475 nm pigment and a 100-fold decrease in the pigment's ability to bind chloride. Increasing the concentration of chloride results in the stabilization of the protonated state of this residue in the chloride binding site and thus increased chloride binding with an accompanying increase in the Schiff base pK.

Animals↗

PubMed1999

Characterization of a mutant pancreatic eIF-2alpha kinase, PEK, and co-localization with somatostatin in islet delta cells.

Phosphorylation of eukaryotic translation initiation factor-2alpha (eIF-2alpha) is one of the key steps where protein synthesis is regulated in response to changes in environmental conditions. The phosphorylation is carried out in part by three distinct eIF-2alpha kinases including mammalian double-stranded RNA-dependent eIF-2alpha kinase (PKR) and heme-regulated inhibitor kinase (HRI), and yeast GCN2. We report the identification and characterization of a related kinase, PEK, which shares common features with other eIF-2alpha kinases including phosphorylation of eIF-2alpha in vitro. We show that human PEK is regulated by different mechanisms than PKR or HRI. In contrast to PKR or HRI, which are dependent on autophosphorylation for their kinase activity, a point mutation that replaced the conserved Lys-614 with an alanine completely abolished the eIF-2alpha kinase activity, whereas the mutant PEK was still autophosphorylated when expressed in Sf-9 cells. Northern blot analysis indicates that PEK mRNA was predominantly expressed in pancreas, though low expression was also present in several tissues. Consistent with the high levels of mRNA in pancreas, the PEK protein was only detected in human pancreatic islets, and the kinase co-localized with somatostatin, a pancreatic delta cell-specific hormone. Thus PEK is believed to play an important role in regulating protein synthesis in the pancreatic islet, especially in islet delta cells.

Amino Acid Sequence↗

PubMed1999

Electrostatic interactions during activation of coagulation factor IX via the tissue factor pathway: effect of univalent salts.

Interaction between the Gla-domain of coagulation proteins and negatively charged phospholipid membranes is essential for blood coagulation reactions. The interaction is calcium-dependent and mediated both by electrostatic and hydrophobic forces. This report focuses on the electrostatic component of factor IX activation via the extrinsic pathway. Effective charges during the reaction are measured by ionic titration of activity, according to the Debye-Huckel and Gouy-Chapman models. Rates of activation decrease with ionic strength independently of the type of monovalent salt used to control ionic strength. Moreover, the effect of ionic strength decreases at concentrations of charged phospholipid approaching saturation levels, indicating that membrane charges participate directly in the ionic interaction measured. The effective charge on calcium-bound factor IX during activation on phospholipid membranes is 0.95+/-0.1. Possible sites mediating contacts between the Gla-domain and membranes are selected by geometrical criteria in several metal-bound Gla-domain structures. A pocket with a solvent opening-pore of area 24-38 A2 is found in the Gla-domain of factors IX, VII, and prothrombin. The pocket contains atoms with negative partial charges, including carboxylate oxygens from Gla residues, and has a volume of 57-114 A3, sufficient to accommodate additional calcium atoms. These studies demonstrate that electrostatic forces modify the activity coefficient of factor IX during functional interactions and suggest a conserved pocket motif as the contact site between the calcium-bound Gla-domain and charged membranes.

Binding Sites↗

PubMed1999

Single-molecule fluorescence spectroscopy of enzyme conformational dynamics and cleavage mechanism.

Fluorescence resonance energy transfer and fluorescence polarization anisotropy are used to investigate single molecules of the enzyme staphylococcal nuclease. Intramolecular fluorescence resonance energy transfer and fluorescence polarization anisotropy measurements of fluorescently labeled staphylococcal nuclease molecules reveal distinct patterns of fluctuations that may be attributed to protein conformational dynamics on the millisecond time scale. Intermolecular fluorescence resonance energy transfer measurements provide information about the dynamic interactions of staphylococcal nuclease with single substrate molecules. The experimental methods demonstrated here should prove generally useful in studies of protein folding and enzyme catalysis at single-molecule resolution.

Base Sequence↗

PubMed1999

Stereospecific synthesis, structure-activity relationship, and oral bioavailability of tetrahydropyrimidin-2-one HIV protease inhibitors.

The use of tetrahydropyrimidinones as an alternate scaffold for designing HIVPR inhibitors has advantages, over the previously disclosed hexahydro-1,3-diazepin-2-ones, of being more unsymmetrical (different P1/P1'), less crystalline, more soluble, and more lipophilic (mono-ol vs diol). They show a better translation of Ki to IC90 for the more polar P2 groups that in general give the more potent enzyme inhibitors. Structure-activity relationship (SAR) studies of the tetrahydropyrimidinones showed that the phenylethyl P1' substituent, the hydroxyl group, and the urea carbonyl are all critical for good activity. However, there was significant flexibility in the possible P2/P2' substituents that could be used. Many analogues that contained identical or different P2/P2' substituents, or only one P2 substituent, were found to have excellent enzyme potency and several had excellent antiviral potency. Several of these compounds were examined for oral bioavailability in the rat or the dog at 10 mg/kg. However, the oral bioavailability of the tetrahydropyrimidinones was, in general, less than the corresponding hexahydro-1,3-diazepin-2-ones. Unfortunately, when all factors are considered, including potency, protein binding, solubility, bioavailability, and resistance profile, the tetrahydropyrimidinones did not offer any advantage over the previously disclosed hexahydro-1,3-diazepin-2-ones series.

Administration, Oral↗

PubMed1999

Expression of the c-kit proto-oncogene in rat hepatic allografts during acute rejection.

The role of the c-kit proto-oncogene in organ allograft rejection is not known. We investigated the level of c-kit expression following allogeneic transplantation of ACI rat liver grafts into LEW recipients. We studied c-kit mRNA and protein expression in groups of transplant recipients receiving hepatic isografts, hepatic allografts, or hepatic allografts after donor-specific blood transfusion (DST). Pretransplantation DST significantly prolonged survival of hepatic allografts. Infiltrates expressing c-kit were observed in allografts to untreated rats but not in groups receiving isografts or allografts following DST. Northern analysis also demonstrated abundant c-kit mRNA transcripts in the untreated allograft group in contrast to the isograft and the DST-treated groups. In addition, significantly more transcripts for interleukin-12 (IL-12), which is synergistic with c-kit, were present in untreated than in DST-treated allograft groups. In contrast, transforming growth factor beta (TGF-beta), which inhibits c-kit synthesis, was expressed abundantly in hepatic allografts to DST-treated rats but not in allografts to untreated animals. Transcripts for IL-10, which inhibits IL-12 production, were significantly more plentiful in hepatic allografts following DST than in those without DST. The results suggest that c-kit proto-oncogene expression in infiltrating cells is associated with rat hepatic allograft rejection.

Animals↗