Biomedical subjects

L Guo

Publications and source records attributed to L Guo.

At least 181 records · Page 10Linked to original sources

PubMed1999

Expression of growth hormone and insulin-like growth factor in the immune system of children.

Our objective was to study the effect of the growth hormone--insulin-like growth factor axis on the development of the immune system in children. We used radio receptor analysis, dot blot, in situ hybridization, and immunohistochemical techniques to determine the expression and distribution of growth hormone and growth hormone receptors, insulin-like growth factors, receptors and binding proteins in the thymus, lymph nodes and peripheral blood lymphocytes of children and adults. Our results showed that almost all components of the growth hormone-insulin-like growth factor axis were expressed in immune organs and cells, but the levels of expression varied. Growth hormone, insulin-like growth factor I, and insulin-like growth factor-binding proteins 1-6 were produced by immune cells in autocrine or paracrine ways. The expression of growth hormone receptors on peripheral blood lymphocytes was to be age-related. The growth hormone-insulin-like growth factor axis may help regulate the development and function of the immune system in children.

Adolescent↗

PubMed1999

Determination of organochlorine and organophosphate pesticide residues in fruits, vegetables and sediments.

A method is described for the determination of organochlorine and organophosphate pesticide residues in fruits, vegetables and sediments. The concentrated solvent extract was sealed in a polymeric membrane tube, dialysed in cyclohexane and the solvent replaced with hexane. The organophosphates were analysed on a specific thermionic detector without further clean-up. For the organochlorine pesticides the extract was eluted through 3 g of alumina and analysed on GC/ECD. The clean-up for sediment extract was carried out on a 10 g alumina column with 100 mL hexane containing 5% acetone and the eluate was concentrated to 5 mL. The detection limit for organophosphates on a 40 g sample and a final volume of 10 mL was on the average 0.01 mg/kg. The detection limit for organochlorine pesticides, with the final volume of 25 mL, was 0.005 mg/kg for all pesticides except for p,p'-DDT and endosulfan sulphate, which was 0.01 mg/kg. The detection limit for organochlorine pesticides in sediment, with the final volume of 2 mL, was less than 1 microgram/kg and for organophosphate pesticides less than 10 micrograms/kg when the final volume was made to 0.5 mL. At the detection limits the method produced a very high coefficient of variation for both organochlorine and organophosphate pesticides.

Chromatography, Gas↗

PubMed1999

Use of arbitrarily primed polymerase chain reaction to study Salmonella ecology in a turkey production environment.

Turkeys, liners, waterers, litter, air, and feed weighbacks were sampled for Salmonella. Salmonella species S. simsbury, S. kentucky, S. montevideo, S. senftenberg, and S. ealing were identified at a rate of 54.9, 38.0, 2.8, 2.8, and 1.4% respectively. All isolates were subjected to Salmonella-specific polymerase chain reaction (PCR) and were confirmed as Salmonella-positive by the predicted product, a 457-bp DNA fragment. Biofingerprint patterns of each isolate were generated using arbitrary primer sets, LG6+LG8 and LG6+LG9. These primer sets differentiated between Salmonella serotypes except for S. simsbury and S. senftenberg. No differences in fingerprint patterns were observed among farm isolates that were the same serotype. This similarity suggested that these isolates were from a common origin or that primer sets could not distinguish isolates at the subserotype level. Frequency of Salmonella isolation decreased from Week 10 to 18 of the growout period. Resistance of older birds to Salmonella colonization, due to a more mature gut microflora, may account for this observation. Results demonstrate that arbitrarily primed-PCR (AP-PCR) can effectively differentiate among serotypes except for S. simsbury and S. senftenberg; results regarding potential to differentiate at the subserotype level were inconclusive.

Animals↗

PubMed1999

Vacuum-assisted closure in the treatment of degloving injuries.

Degloving injuries range from the occult, easily missed injury to obvious massive tissue damage. The serious nature of these wounds is exacerbated by mismanagement. It is generally accepted that the degloved tissue should be excised, defatted, fenestrated, and reapplied as a full-thickness skin graft. Dressings are required that provide gentle, evenly distributed pressure and avoid shear stress to the newly grafted skin. Numerous types of dressings have been devised but all are cumbersome and time-consuming. We have found the Vacuum-Assisted Closure device to be a rapid, effective, and easy-to-use alternative to traditional methods. The authors examine their experience using a vacuum-assisted closure device to treat nine degloving injuries in 5 patients and discuss the important aspects in using this technique.

Adult↗

PubMed1999

Epidemiologic determination of community-based nursing case management for stroke.

Efforts to control costs, especially those resulting from the 1997 Balanced Budget Act, have resulted in profound opportunities for futuristic community-based nursing care. A retrospective chart review was conducted on 1,992 stroke patients discharged from 15 Cincinnati hospitals from July 1, 1995, to June 30, 1996. Determinants and descriptors of stroke distribution were identified. This study shows how nurses can plan cost-effective care while maintaining quality through an epidemiologic assessment of patient, family, and community needs.

Aged↗

PubMed1999

Epitope mapping of monoclonal antibodies against Bordetella pertussis adenylate cyclase toxin.

Adenylate cyclase (AC) toxin from Bordetella pertussis is a 177-kDa repeats-in-toxin (RTX) family protein that consists of four principal domains; the catalytic domain, the hydrophobic domain, the glycine/aspartate-rich repeat domain, and the secretion signal domain. Epitope mapping of 12 monoclonal antibodies (MAbs) directed against AC toxin was conducted to identify regions important for the functional activities of this toxin. A previously developed panel of in-frame deletion mutants of AC toxin was used to localize MAb-specific epitopes on the toxin. The epitopes of these 12 MAbs were located throughout the toxin molecule, recognizing all major domains. Two MAbs recognized a single epitope on the distal portion of the catalytic domain, two reacted with the C-terminal 217 amino acids, one bound to the hydrophobic domain, and one bound to either the hydrophobic domain or the functionally unidentified region adjacent to it. The remaining six MAbs recognized the glycine/aspartate-rich repeat region. To localize these six MAbs, different peptides derived from the repeat region were constructed. Two of the six MAbs appeared to react with the repetitive motif and exhibited cross-reactivity with Escherichia coli hemolysin. The remaining four MAbs appeared to interact with unique epitopes within the repeat region. To evaluate the roles of these epitopes on toxin function, each MAb was screened for its effect on intoxication (cyclic AMP accumulation) and hemolytic activity. The two MAbs recognizing the distal portion of the catalytic domain blocked intoxication of Jurkat cells by AC toxin but had no effect on hemolysis. On the other hand, a MAb directed against a portion of the repeat region caused partial inhibition of AC toxin-induced hemolysis without affecting intoxication. In addition, the MAb recognizing either the hydrophobic domain or the unidentified region adjacent to it inhibited both intoxication and hemolytic activity of AC toxin. These findings extend our understanding of the regions necessary for the complex events required for the biological activities of AC toxin and provide a set of reagents for further study of this novel virulence factor.

Adenylate Cyclase Toxin↗

PubMed1999

Rho3 of Saccharomyces cerevisiae, which regulates the actin cytoskeleton and exocytosis, is a GTPase which interacts with Myo2 and Exo70.

The Rho3 protein plays a critical role in the budding yeast Saccharomyces cerevisiae by directing proper cell growth. Rho3 appears to influence cell growth by regulating polarized secretion and the actin cytoskeleton, since rho3 mutants exhibit large rounded cells with an aberrant actin cytoskeleton. To gain insights into how Rho3 influences these events, we have carried out a yeast two-hybrid screen using an S. cerevisiae cDNA library to identify proteins interacting with Rho3. Two proteins, Exo70 and Myo2, were identified in this screen. Interactions with these two proteins are greatly reduced or abolished when mutations are introduced into the Rho3 effector domain. In addition, a type of mutation known to produce dominant negative mutants of Rho proteins abolished the interaction with both of these proteins. In contrast, Rho3 did not interact with protein kinase C (Pkc1), an effector of another Rho family protein, Rho1, nor did Rho1 interact with Exo70 or Myo2. Rho3 did interact with Bni1, another effector of Rho1, but less efficiently than with Rho1. The interaction between Rho3 and Exo70 and between Rho3 and Myo2 was also demonstrated with purified proteins. The interaction between Exo70 and Rho3 in vitro was dependent on the presence of GTP, since Rho3 complexed with guanosine 5'-O-(3-thiotriphosphate) interacted more efficiently with Exo70 than Rho3 complexed with guanosine 5'-O-(3-thiodiphosphate). Overlapping subcellular localization of the Rho3 and Exo70 proteins was demonstrated by indirect immunofluorescence. In addition, patterns of localization of both Exo70 and Rho3 were altered when a dominant active allele of RHO3, RHO3(E129,A131), which causes a morphological abnormality, was expressed. These results provide a direct molecular basis for the action of Rho3 on exocytosis and the actin cytoskeleton.

Actins↗

PubMed1999

Endocrine characteristics of human breast epithelial cells, MCF-10F.

MCF-10F is a spontaneously immortalized nontransformed human breast epithelial cell line which does not grow in soft agar or form tumors in nude mice. Though the presence of estrogen receptors has not been found in these cells, they can metabolize estradiol very efficiently. The present study describes the endocrine characteristics of this cell line with respect to growth response to estradiol and its metabolites, estradiol metabolism and aromatase activity. MCF-10F cells were growth stimulated by 16alpha-hydroxyestrone and estriol, whereas, estradiol and other estradiol metabolites did not affect cell proliferation. The constitutive level of 16alpha-hydroxyestrone, a metabolite of estradiol biotransformation that has been associated with enhanced carcinogenesis in several animal, cell and tissue culture models, was a hundredfold higher in the non-transformed MCF-10F cells than in the transformed MCF-7 cells. Treatment with the carcinogen, dimethylbenz(a)anthracene (DMBA), however, did not upregulate 16alpha-hydroxylation as was observed in transformed MCF-7 cells. MCF-10F cells also had no detectable aromatase activity though the level of 17-oxidation was unusually high as compared with MCF-7 cells. Our results using the non-transformed MCF-10F cells as a model system suggests that the presence of high level of 16alpha-hydroxyestrone, a metabolite previously shown to be associated with malignant phenotype, may not be sufficient for breast cancer transformation.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1999

Extracellular Ca2+ increases cytosolic free Ca2+ in freshly isolated rat odontoblasts.

Recent evidence suggests that extracellular Ca2+ may modulate cell function in mineralized tissue. To determine whether dentinogenic cells, in particular, are sensitive to extracellular Ca2+, fura-2 microfluorometry was used to monitor intracellular calcium levels in odontoblasts freshly isolated from rat incisor. In response to applications of 0.5-4.0 mM extracellular calcium (CaCl2), most odontoblasts (84%; 107/128) showed an increase in intracellular calcium. For the majority of these cells (70%; 75/107), the typical response was biphasic; there was an initial, transient increase in intracellular calcium which reached peak levels within 30-50 s and decayed rapidly, followed by a slower (> 300 s) recovery toward basal levels. In general, the response of these cells to calcium was repeatable and the mean calcium concentration for the half-maximal response was approximately 1.3 mM. This effect could be partially blocked by either 200 microM lanthanum, a nonspecific blocker of Ca2+ channels, or 20 microM dantrolene, a potent inhibitor of Ca2+ release from internal stores. Used in combination, lanthanum, and dantrolene nearly abolished the calcium response completely. In addition, this response was sensitive to the dihydropyridine-sensitive calcium channel blocking agent nicardipine (60 microM), indicating a role for voltage-gated calcium channels during these events. These results show that odontoblasts respond to external calcium through mechanisms involving both influx of external calcium as well as release of calcium from internal stores and suggest a role for extracellular calcium in regulating the function of these cells.

Animals↗

PubMed1999

Preventive and therapeutic effect of tumor derived heat shock protein, gp96, in an experimental prostate cancer model.

Tumor-derived purified heat shock protein (HSP), gp96, has tumor protective effect in a number of experimental cancers that include fibrosarcoma, hepatoma, and spindle cell carcinoma. The rationale for using gp96 as a vaccinating agent stems from the discovery that HSPs, including gp96, chaperone antigenic peptides for eventual recognition and elicitation of an immune response. The immune response generated by the HSP-peptide complex is specific to the tumor from which they are derived. The long-term objective of our studies is to develop a vaccine for primary and metastatic prostate cancer using tumor-derived HSPs. In the present study, we report our results on the tumor protective effect of irradiated Dunning G cells, or purified preparations of g96-peptide complexes as a tumor vaccine. Tumor incidence, latency, and tumor growth were the end points of measurement. Tumor bearing Copenhagen rats, made free of disease by surgical resection of the tumors resisted a fresh challenge of live Dunning G tumor cells. Vaccination with irradiated whole cells failed to elicit any resistance to tumor growth. Vaccination with Dunning G derived purified gp96-peptide complexes delayed both incidence and growth of Dunning G induced tumors. Inhibition of tumor growth was observed when gp96 was administered after tumor induction. Our data suggests that tumor derived gp96-peptide complexes can be used as an effective prophylactic and therapeutic agent even in poorly immunogenic cancer such as prostate cancer. Further investigations will determine specificity of action and define the immunological determinants and experimental conditions for its optimal activity.

Animals↗

PubMed1999

[The correlation between t(14;18) chromosomal translocation and hepatocarcinoma].

OBJECTIVE: To study the correlation between t(14;18) chromosomal translocation and the occurrence of hepatocarcinoma. METHODS: bcl-2/JH fusion gene in 54 cases of hepatocarcinoma including 40 cases of hepatocellular carcinoma(HCC) and 14 cases of cholangicellular carcinoma (CCC) were investigated using seminested in situ PCR. RESULTS: Bcl-2/JH fusion gene was present in 25% (10/40) HCC and negative in CCC. CONCLUSION: These findings indicated that t(14;18) chromosomal translocation might play a role in the pathogenesis of HCC but seemed to bear no relation with CCC. mbr and mcr are the two important breakpoints of bcl-2 gene in HCC.

Carcinoma, Hepatocellular↗

PubMed1999

Age-dependent variation in metalloproteinase activity of isolated human Bruch's membrane and choroid.

PURPOSE: To characterize and determine the effect of aging on the matrix metalloproteinase (MMP) component of the extracellular matrix-remodeling mechanism of isolated human Bruch's-choroid. METHODS: Immunohistochemical techniques and western blot analysis were used to detect and localize various members of the MMP family of proteolytic enzymes in the Bruch's-choroid complex. Gelatin substrate zymography was used to detect and quantify the levels of MMP-2 and -9 in homogenates of Bruch's-choroid from both macular and peripheral regions of the human fundus. Aging alterations in these enzymes were quantified by densitometric analysis of photographic negatives of the zymography gels. RESULTS: Intact preparations of Bruch's-choroid showed the presence of inactive forms of two gelatinases (MMP-2, 65 kDa, and MMP-9, 92 kDa), interstitial collagenase (MMP-1, 52 kDa) and stromelysin (MMP-3, 57 kDa). MMP-1 and -3 were localized primarily to Bruch's membrane. MMP-9 was distributed evenly in Bruch's membrane with some patchy presence in the choroidal mass. Distribution of MMP-2 was similar to that of MMP-9, but the staining in Bruch's was much fainter. On gelatin zymography, an active form of MMP-2 (58-kDa species) was frequently observed in peripheral samples but only occasionally in macular regions. The levels of MMP-2 and -9 increased with aging in both the macular and the peripheral regions of the fundus (P < 0.05). MMP-2 levels were lower in macular regions than in the periphery but no such variation was observed with MMP-9. Both these inactive gelatinases could be activated in vitro. CONCLUSIONS: A matrix-degrading mechanism essential for extracellular remodeling was shown to be present in Bruch's membrane. In macular regions, increasing levels of inactive forms of metalloproteinase and scarcity of active forms of MMP-2 suggests possible involvement of impaired extracellular degradation in both aging and macular degeneration.

Adolescent↗

PubMed1999

[Analysis of fusion points in hybrid genes and gene deletion for congenital red-green color vision defects].

OBJECTIVE: To investigate gene deletion and the fusion points of hybrid genes in congenital red-green color vision defects. METHODS: Genomic DNA was collected from 11 protans, 19 deutans and 5 normal controls. Promoter and exons 2-5 of the red and green pigment genes in these subjects were analyzed by using PCR-Heteroduplex-SSCP analysis. The origin and component of each individual gene were determined by comparison with the patterns of known sequence of the red and green visual pigment genes. RESULTS: Fourteen out of the 30 patients with red-green color vision defects were found to have hybrid gene. The fusion points of the hybrid gene were located in exon 1-intron 1(4 cases), introns 2-3(5 cases) and intron 4 (5 cases). CONCLUSION: The fusion point of a hybrid gene may occur in exon 1-intron 1 and intron 4 as well as in introns 2-3(including exon 3).

Artificial Gene Fusion↗

PubMed1999

Ring-constrained orvinols as analogs of buprenorphine: differences in opioid activity related to configuration of C(20) hydroxyl group.

The relative positions of the C(20) substituents in buprenorphine, particularly the hydroxyl group, have been implicated in its actions as a partial mu-agonist and a kappa-antagonist. This hypothesis has been examined by the synthesis and pharmacological characterization of five orvinols in which the C(20) carbon atom of buprenorphine is constrained in a five-membered ring, fixing the hydroxyl group above (beta) or below (alpha) the plane of the ring. All five compounds were nonselective in binding assays with similar, low nanomolar affinities. The compounds acted as delta-agonists in the mouse vas deferens and kappa-agonists in the myenteric plexus-longitudinal muscle of the guinea pig ileum and in Chinese hamster ovary (CHO) cells expressing the human kappa-opioid receptor (CHO-hkor). All were lower efficacy mu-agonists than buprenorphine as measured by the [(35)S]guanosine-5'-O-(3-thio)triphosphate assay in SH-SY5Y cells. The major difference between the isomers was an 11- to 12-fold higher potency of the beta-OH isomer (BU46) compared with the alpha-OH isomer (BU47) at the kappa-receptor in the guinea pig ileum and CHO-hkor cells and a somewhat higher efficacy of BU46 in CHO-hkor cells. BU46 and BU47 were evaluated in vivo. BU46 was a full agonist in the mouse writhing assay and antinociception was prevented by norbinaltorphimine, showing a kappa-mechanism of action. In contrast, BU47 acted as an antagonist of mu-, delta-, and kappa-mediated antinociception in the writhing assay. The results show that the configuration of the hydroxyl group is not important in binding affinity at mu-, delta-, or kappa-receptors but does influence kappa-potency and kappa-efficacy, particularly in vivo.

Analgesics, Opioid↗

PubMed1999

Retroviruses in autoimmune liver disease: genetic or environmental agents?

Retroviruses have been implicated in the pathogenesis of several human autoimmune conditions including Sjögren's syndrome, primary biliary cirrhosis, immune mediated diabetes, and multiple sclerosis. The human intracisternal A type particle derived from Sjögren's syndrome patients' salivary glands was the first retrovirus to be isolated from a human autoimmune disorder but the agent has yet to be cloned. In primary biliary cirrhosis patients, virus like particles have been observed by electron microscopy in biliary epithelium, endogenous retroviral sequences have been cloned from liver samples, and antibody reactivity to the human intracisternal A type particle has been observed in the majority of patients tested. However, there is no evidence to link the endogenous retroviral sequences in primary biliary cirrhosis patients to the retroviral antibody reactivity or virus like particles. In other patients with liver disease, reactivity to the human intracisternal A type particle was observed in a small but significant proportion of patients with hepatitis C virus infection. If the intracisternal A type particle is an endogenous retrovirus, it is interesting to speculate that hepatitis C virus infection may modulate the endogenous retroviral expression, as chronic hepatitis C has been linked with the development of Sjögren's syndrome. Furthermore, many patients with chronic hepatitis C virus infection have reactivity to an autoantigen of unknown significance known as GOR that has protein sequence homology with both hepatitis C virus nucleocapsid protein as well as HTLV-1 gag. This may be an another example of an endogenous retroviral protein acting as an autoantigen in liver disease patients. At this time, there is little evidence to suggest that endogenous retroviruses are infectious agents that cause autoimmune disease but they may be implicated as either genetic elements or antigens. Further studies will be required to characterize the role that both exogenous and endogenous retroviruses play in the pathogenesis of autoimmune liver diseases.

Amino Acid Sequence↗

PubMed1999

Expression of nerve growth factor from Agkistrodon halys Pallas in E. coli and its purification.

The nerve growth factor (NGF) gene of Agkistrodon halys Pallas was cloned into a secretive prokaryotic expression vector pET-22b+ which carried a C-terminal His. Tag sequence. After transforming into E. coli BL21 (DE3), NGF was induced to express at 30 degrees C by IPTG. SDS-PAGE analysis showed an induced expression product band which constituted about 20% of the total bacterial proteins. However, its molecular weight was larger than what was expected. Moreover, the analysis of product solubility revealed that NGF was in the form of inclusion bodies. The inclusion bodies were solubilized in 6 mumol/L guanidine HCl and purified directly by immobilized metal (Ni2+) chelation affinity chromatography. The product was renatured by dilution and air oxidation in the presence of 5 mumol/L CuSO4, and was proved active by examining the survival rate of PC12 cells in a serum-free medium.

Agkistrodon↗

PubMed1999

An animal and clinical study on the change of neuropeptide Y release evoked by electrical stimulation and myocardial ischemia.

OBJECTIVE: To investigate the change characteristics of neuropeptide Y (NPY) release during acute myocardial ischemia period. METHODS: The animal test was carried out in in situ perfused guinea pig hearts with intact sympathetic innervation. Electrical stimulation-evoked exocytotic release of NPY during ischemia and reperfusion was tested by radioimmunoassay (RIA). The plasma NPY concentrations were measured in patients with acute myocardial infarction (AMI) and angina pectoris (AP) in different times. RESULTS: Electric stimulation of the left ganglion in guinea pig heart evoked an exocytic release of neuropeptide Y. Stimulation after 20 minutes of global ischemia (S2), compared with control period stimulation (S1) produced the inhibition of NPY to a certain extent (S2/S1: 0.72, P < 0.05), whereas the inhibition of NPY release disappeared after 5 minutes reperfusion (with S2/S1 of 1.01, P > 0.05). Ischemia alone, without the electric stimulation, did not apparently induce NPY release. The clinical test found that the plasma NPY level was increased significantly during the acute ischemia attack period of coronary heart disease (CHD). The plasma NPY level reached peak (136.3 +/- 66.5 pg/ml) in patients during the first day after AMI. It began to decrease from the third day and came to normal level in the end of the first week. The plasma NPY level was 159.3 +/- 98.5 pg/ml in AP patients during angina attack. After two weeks treatment, the plasma NPY level was decreased to 118.9 +/- 54.3 pg/ml (P < 0.05). CONCLUSIONS: The NPY release of global ischemia have some relation with sympathetic nerve activity. At the early stage of ischemia, NPY release is inhibited to some degree and the inhibition factors will fade away on reperfusion. NPY interferes with the pathogenesis and the pathophysiolgy.

Aged↗

PubMed1999

[Multivariate analysis of clinical factors in restenosis after coronary interventional treatment].

OBJECTIVE: To found the independent predictors for restenosis after coronary interventional treatment. METHODS: Quantitative angiography was performed in 103 patients(128 successfully dilated lesions) at angioplasty and at 6-month follow-up, and then univariate analysis and multivariate logistic regression analysis were performed to identify correlates of restenosis with clinical factors. RESULTS: The total restenosis rate was 39.8% (51 of 128 lesions). According to univariate analysis, the patients who had undergone coronary tenting > or = 3.5 mm had a lower rate of restenosis(3/29 and 6/30) and the others with the ACC/AHA lesion type B and C(46/51 and 51/77), collateral circulation to the obstruction set(17/51 and 2/77), high percentage diameter stenosis before PTCA(86 +/- 14)% and (79 +/- 15)%, and high maximal inflation pressure(8.3 +/- 2.1) kPa and (7.4 +/- 1.7) kPa had a higher rate of restenosis (P < 0.01). Stable angina showed a low restenosis rate (3/29 and 6/30). The less minimal lumen diameter before(0.43 +/- 0.41) mm and (0.66 +/- 0.43) mm and after PTCA(2.56 +/- 0.55) mm and (2.85 +/- 0.59) mm, had the higher the restenosis rate (P < 0.05). Multivariate logistic regression analysis showed that coronary stenting had a low rate of restenosis, and that lesion type B and C, high percentage diameter stenosis before PTCA, high maximal inflation pressure, and male had a high rate of restenosis. CONCLUSION: Coronary stent, percentage diameter stenosis before PTCA, lesion type, maximal inflation pressure, and sex were independent predictors for restenosis.

Aged↗