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Biomedical subjects

J Fan

Publications and source records attributed to J Fan.

At least 307 records · Page 17Linked to original sources
PubMed1994

Activation and cholesterol accumulation of macrophages induced by hypercholesterolemia. A study using a rat peritoneal macrophage model for extravascular in vivo generation of foam cells.

Intimal infiltration of lipid-filled macrophages (M psi s) is an important event in the pathogenesis of atherosclerosis. To better understand M psi functions, a model for the extravascular in vivo generation of foam cells in rat peritoneal cavities was utilized. Morphologic alterations, intracellular cholesterol accumulation, subpopulation, activation and proliferative properties of M psi from hypercholesterolemic rats (HM psi s) were compared with M psi s from normal rats (NM psi s). HM psi s revealed a significant increase of cholesterol mass in the cytoplasm; 65% of HM psi s were loaded with various amounts of oil-red-O-stainable lipid droplets which were barely identified in NM psi s. Ultrastructurally, accumulated lipid droplets in HM psi s were either membrane-bound or membrane-free in the cytoplasm. Further biochemical analysis revealed that cellular levels of total cholesterol, free cholesterol, and cholesteryl esters in HM psi s were increased 6-, 8-, and 4-fold, respectively. As to the M psi subpopulation, there was a significant increase of Ia-antigen-positive cells in HM psi s (15.8 vs. 8.8%), indicating that these cells were in a state of activation. To investigate the mitotic activity, the proliferative potential of M psi s was determined both in vivo and in vitro using monoclonal anti-bromodeoxyuridine (anti-BrdU) antibody to detect BrdU incorporated into cell DNA. However, both NM psi s and HM psi s showed little proliferation; proliferative indices were less than 2%. This implies that M psi s are barely replicating, and hypercholesterolemia does not stimulate M psi s in this aspect.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Differential tissue regulation of insulin-like growth factor-I content and binding proteins after endotoxin.

The purpose of the present study was to investigate the regulation of plasma and tissue levels of insulin-like growth factor-I (IGF-I) and IGF-binding protein-1, -2, and -3 (IGFBP-1, -2, and -3) in rats injected with Escherichia coli lipopolysaccharide (LPS), a component of the outer cell wall of gram-negative bacteria. When injected iv into conscious overnight fasted rats, plasma IGF-I levels were initially decreased within 1 h, maximally depressed at 4 h, and still only 35-45% of control values at 24 h. GH levels were reduced as early as 30 min after LPS, averaged 80-90% of control values between 1-4 h, but had returned to basal levels by 24 h. The magnitude and duration of these changes were similar regardless of whether 100 or 10 micrograms/100 g BW (LD20 and LD0, respectively) LPS were injected. Plasma levels of IGFBP-1 and a 28K mol wt BP (BP-28K) were elevated 2- to 3-fold 4 h after LPS treatment, whereas IGFBP-3 and -2 levels were unchanged. The elevation in plasma IGFBP-1 and IGFBP-28K was observed as early as 1 h and was sustained for up to 24 h after LPS treatment. IGF-I levels were decreased 30-50% in liver, pituitary, and skeletal muscle, unchanged in brain, and elevated 5-fold in kidney in response to LPS. Of the tissues sampled, IGFBP-3 and -2 were selectively elevated in liver after LPS treatment. IGFBP-1 was increased in liver, muscle, and kidney in response to LPS. The level of the 28,000 mol wt BP was increased in liver (83%) and not changed in muscle or brain. These data indicate that LPS produces both rapid and sustained alterations in circulating levels of GH, IGF-I, and IGFBPs. Furthermore, there were marked tissue-specific changes in levels of IGF-I and IGFBPs. LPS-induced changes in plasma and tissue IGFBP-3 were not regulated by changes in GH, and changes in insulin could not explain the alterations in IGFBP-1 and -2. These results suggest that after the injection of LPS, changes in IGF-I and IGFBP levels are regulated by a mechanism(s) different from those previously described.

Animals↗
PubMed1994

[Clinical application of rhombotrapezious island musculocutaneous flap for skull base and/or craniomaxillary operation with malignant tumor].

Regional pedicled musculocutaneous flaps are the mainstay of the head and neck reconstruction. They provide a rapid, highly reliable and single-staged technique that is applicable in most cases. The rhombotrapezious island musculocutaneous flap is valuable in the base and craniomaxilloface reconstruction. In this study we updated our experience with the rhombotrapezious island musculocutaneous flap (RTIMF) in 6 cases from 1989 to 1993. Dissections were performed on 9 cadavers, 4 preserved and 5 fresh, yielding 18 pairs or dorsal scapular and transverse cervical artery for evaluation. In the five fresh cadavers, the arteries were selectively cannulated and injected with colored latex. 67% with dorsal scapular and transverse cervical artery commonly arose from the thyro-cervical trunk. 33% with the dorsal scapular artery directly arose from the second part of the subclavian artery. In the period of 1989-1993, 6 rhombotrapezious island musculocutaneous flaps with vascularized pedicle were used for immediate repair in the skull base or craniomaxillary cancer operations. There was no complication of the flaps. Donor site complications were relatively minor. The disturbance in shoulder function was well tolerated. We advocated the incorporation of both the greater and lesser rhomboid muscle to form the compound rhombotrapezious flaps to enhance the vascular supply to the overlying skin. The major advantage of the RTIMF are that it provides a long paddle of thin pliant, hairless skin and muscle that can be rotated as far as the craniomaxilloface and scalp in a single stage. It offers the longest arc of rotation and thus the greatest versatility for the skull base or craniomaxillary reconstruction.

Adult↗
PubMed1994

[Application of polymerase chain reaction for quick assay of herpes simplex viral acute ocular infection and ganglionic latent infection].

Polymerase chain reaction (PCR) was applied as a quick assay for herpes simplex virus-I (HSV-I) ocular infection and trigeminal ganglionic latent infection. A pair of primers derived from the sequence of HSV-I latency associated transcript (LAT) gene were designed and synthesized to detect HSV-I DNA, the gene fragment increased being 452bp. The primers were used for the assays of 30 corneal swabs taken from experimental rabbits with herpes simplex keratitis (HSK), 28 ocular swabs from 23 patients with HSK and from 5 with HSV lid infection and 8 trigeminal ganglionic specimens from experimental rabbits with quiet HSK. Simultaneously, the tissue cultures of all the same above specimens were made. The results of PCR were compared with those of the tissue culture. The comparison indicates that PCR is specific and sensitive. It not only can be used as a quick assay and an objective criterion for clinical diagnosis of HSK, but also can be applied as a powerful weapon for investigation of HSV-I latent infection.

Animals↗
PubMed1994

[A seroepidemiological study on sexually transmitted HBV infection].

A seroepidemiological study on HBV infection was conducted among female prostitutes in houses of detention in Guangzhou and Fuzhou in 1989, 1990 to understand the situation of sexually transmitted HBV infection in selected areas of China, and prevalence of HBV infection in sexual misbehavior populations. The incidence of HBV infection was 84.82% among the population, and 21.6% was HBsAg positive. The prevalence of HBsAg was significantly higher in prostitutes than in pregnant women. The results show that there is a relatively serious HBV infection in prostitutes in certain cities along coastal region in China.

Adolescent↗
PubMed1994

Effect of glucocorticoid receptor (GR) blockade on endotoxemia in rats.

To study the clinical significance of the decrease of glucocorticoid receptor (GR) in stress and shock, GR was blocked about 80% by mifepristone (RU38486), and the effects of the blockade on the pathological changes of endotoxemia were studied in rats. The results revealed that GR blockade may exacerbate the pathological and pathophysiological changes of endotoxemia: (1) the more rapid drop in arterial blood pressure, (2) the more severe pathological changes involving multiple organs, especially the lung and small intestine, (3) the increase of leukocyte adherence in venules and more pronounced rheological changes in the mesenteric microcirculation, and (4) the striking elevation of serum acid phosphatase (ACP), phospholipase A2 (PLA2) activity, and lipoperoxide (LPO). The changes of serum ACP, PLA2, and LPO in the rats with 80% GR blockade were more marked than in those with 50% GR blockade. Based on these findings, we propose that the decrease in GR during stress and shock might be a contributing factor in the pathogenesis of shock and multiple organ failure (MOF). The possible mechanisms of the above noted findings are discussed.

Acid Phosphatase↗
PubMed1993

Elevated IFN-gamma and decreased IL-2 gene expression are associated with HIV infection.

Because cytokines have a central role in the regulation and function of the human immune system, expression of several key cytokine genes in HIV infection was compared by quantitative polymerase chain reaction studies in lymphocytes from HIV-seronegative and -seropositive subjects. Elevated levels of IFN-gamma mRNA and lowered IL-2 mRNA were found in the PBMC of eight seropositive men with CD4 T cells over 500/mm3 (mean, 647/mm3), whereas IL-4 and IL-10 mRNA were not changed significantly. PBMC obtained 2 yr later from four of these patients with stable disease status (unchanged CD4 T cell number) showed median mRNA levels that were nearer normal for IFN-gamma and for IL-2. Four other men whose CD4 levels fell more than 200/mm3 in the following 2 yr, however, showed increased IFN-gamma and lowered IL-2. Purified CD4 and CD8 T cells from 10 HIV-seropositive and 10 -seronegative homosexual men were compared. Cytokine gene expression was found to be markedly different in CD4 and CD8 T cells from HIV-seropositive men. In CD8 T cells on a per-cell basis, the levels of cytokine mRNA were substantially lower than in CD4 T cells and were not markedly changed in HIV infection. In the CD4 T cells, on a per-cell basis, the mean mRNA levels of IFN-gamma, IL-10, and TNF-alpha were increased substantially (p < 0.001) in HIV infection. IL-2 gene expression was not increased significantly. Thus, the low IL-2 mRNA expression seen in PBMC is primarily due to the reduced CD4 T cell numbers. Increased expression of IFN-gamma genes in CD4 T cells, however, indicates that these cells may be responsible for substantial amounts of circulating IFN-gamma that occur in HIV infection. The striking difference in the effect of HIV infection on the expression of IFN-gamma and IL-2 genes indicates that these cytokines are under separate control. IL-4 mRNA levels were not changed. IL-10 gene expression, however, was increased more in early HIV infection, with less of an increase later. Expression of all cytokines in CD4 T cells appeared to subside late in HIV infection. However, the balance of cytokine expression was altered in all stages of HIV infection.

Adult↗
PubMed1993

Monocyte-endothelial cell interactions in vitro, with reference to the influence of interleukin-1 and tumor necrosis factor.

The interaction between monocytes and endothelial cells plays an important role in normal vascular biology and the pathogenesis of several vascular diseases. In the present study, interactions of freshly isolated human monocytes (Mos) and cultured umbilical vein endothelial cells (ECs) were quantitatively analyzed by a time lapse microcinematographic optical video system in vitro, with reference to Mo locomotion, adherence, and cytokine influence on these processes. The interaction between Mos and ECs was found to be a dynamic process. Without any stimulation of ECs, Mos generally possessed higher binding capacity to ECs and more active motile property than neutrophils and lymphocytes. The binding ratio of Mos to ECs varied from 0 to 8. Mos crawled over the surface of ECs or along the intercellular boundary areas of ECs by extending pseudopodia as long as 60 microns in length to traverse several ECs. Mos migrated into the subendothelium and could cause the disruption of the EC monolayer. In contrast, neutrophils or lymphocytes showed less adhesiveness to ECs and exhibited less dislocation when they moved on the ECs. Pretreatment of ECs with either human recombinant interleukin-1 beta (IL-1 beta) or tumor necrosis factor (TNF) (10-20 U/ml for 4-8 h) significantly increased adhesion rates of both Mos and neutrophils. Furthermore, the increased adhesion of neutrophils to stimulated ECs was accompanied by incremental increases in the rate of cellular movements. These phenomena were found to be associated with activation of EC surface adhesion molecules. In addition, by using the Boyden chamber assay, we found that IL-1 and TNF did not produce any chemotactic activity for Mos with a concentration range of 10(-3) to 10(3) U/ml. These results indicate that, in comparison with neutrophils and lymphocytes, Mos exhibited active adhesive and motive properties even on unstimulated EC surfaces, which could potentially interfere with the integrity of ECs. Upon exposure to cytokine stimulation, ECs increase the expression of adhesion molecules thereby enhancing both adhesion and locomotion of leukocytes. The distinctively higher affinity for binding to cultured ECs of blood Mos and their active motility relative to other circulating leukocytes may have great consequences in various physiological and pathological processes in vivo, including atherogenesis.

Cell Communication↗
PubMed1993

Effects of graded doses of epinephrine during asphxia-induced bradycardia in newborn lambs.

To study the hemodynamic effects of graded doses of epinephrine (EPI) in a newborn animal model of hemodynamically significant bradycardia, we performed the following study. Ten newborn lambs were chronically instrumented with catheters and flow transducers so that systemic, pulmonary arterial, left atrial and right atrial pressures as well as heart rate, cardiac output and left carotid artery flow could be monitored. During each of five asphyxia induced bradycardia episodes, with cardiac output depressed to approximately 30% of baseline, lambs were given either 0, 1, 10, 50, or 100 micrograms of EPI in a randomized sequence. After 30 s, the lambs were resuscitated with room air ventilation while hemodynamic parameters were monitored. During asphyxia and prior to EPI administration, all hemodynamic parameters were similar. In addition, for the first 30 s following EPI administration, hemodynamic parameters continued to deteriorate in a manner that was not influenced by the dose of EPI administered. During the resuscitation period with resumption of ventilation, systemic blood pressure and coronary perfusion pressure rose higher following 50 and 100 micrograms/kg of EPI than after the smaller doses. Heart rate was highest following the 100 micrograms/kg dose. Stroke volume and cardiac output, however, appeared to be blunted by the 100 micrograms/kg dose of EPI with no differences in carotid flow noted by dose of EPI administered. It appears that doses of EPI greater than 10 micrograms/kg, the dose currently recommended by the American Heart Association, may be beneficial as an adjunct in treatment of hemodynamically significant bradycardia. However, doses as high as 100 micrograms/kg may blunt cardiac output and stroke volume and should be used with caution.

Animals↗
PubMed1993

A new hypothesis about the relationship between free radical reactions and hemorheological properties in vivo.

This paper is concerned with a hypothesis that disturbance of free radical reactions may lead to abnormality of hemorheological properties in vivo, and so the free radicals generated in vivo may damage certain tissue cells indirectly by reducing the supply of oxygen and nutrients to these cells through slowing the circulation of blood. This hypothesis is based on the following evidence: A. We have found that the whole blood viscosity at low shear rate correlates to the lipid peroxidation in the patients suffering from certain cardio- or cerebrovascular diseases, and in dogs during liver ischemia reperfusion or hemorrhagic pancreatitis. B. Reports have shown that several alterations of hemorheological properties may take place as a result of free radical reactions, such as lipid peroxidation. For instance, lipid peroxidation may lead to decrease of deformability of red cells, increase of aggregation of red cells, formation of liquid thrombin, etc. C. We have demonstrated that some alterations of hemorheological properties involve the role of free radicals in rats suffering from intestinal ischemia/reperfusion. As evidence for this conclusion, superoxide dismutase (SOD) used as a specific scavenger of superoxide anion radical (O2-) can significantly prevent the intestinal ischemia/reperfusion induced changes of lipid peroxidation, red cell aggregation, Cassion's viscosity and whole blood viscosity at low shear rate in rats.

Animals↗
PubMed1993

The organization of F-actin and microtubules in growth cones exposed to a brain-derived collapsing factor.

In previous work we characterized a brain derived collapsing factor that induces the collapse of dorsal root ganglion growth cones in culture (Raper and Kapfhammer, 1990). To determine how the growth cone cytoskeleton is rearranged during collapse, we have compared the distributions of F-actin and microtubules in normal and partially collapsed growth cones. The relative concentration of F-actin as compared to all proteins can be measured in growth cones by rationing the intensity of rhodamine-phalloidin staining of F-actin to the intensity of a general protein stain. The relative concentration of F-actin is decreased by about one half in growth cones exposed to collapsing factor for five minutes, a time at which they are just beginning to collapse. During this period the relative concentration of F-actin in the leading edges of growth cones decreases dramatically while the concentration of F-actin in the centers decreases little. These results suggest that collapse is associated with a net loss of F-actin at the leading edge. The distributions of microtubules in normal and collapsing factor treated growth cones were examined with antibodies to tyrosinated and detyrosinated isoforms of alpha-tubulin. The tyrosinated form is found in newly polymerized microtubules while the detyrosinated form is not. The relative proximal-distal distributions of these isoforms are not altered during collapse, suggesting that rates of microtubule polymerization and depolymerization are not greatly affected by the presence of collapsing factor. An analysis of the distributions of microtubules before and after collapse suggests that microtubules are rearranged, but their polymerization state is unaffected during collapse. These results are consistent with the hypothesis that the brain derived collapsing factor has little effect on microtubule polymerization or depolymerization. Instead it appears to induce a net loss of F-actin at the leading edge of the growth cone.

Actins↗
PubMed1993

[Study of synthetic peptide antigen in the detection of HIV sero-antibody].

Antigenicity of 13 synthetic HIV peptides were tested by ELISA. The results indicated that CH-10 was the most antigenetic peptide as compared with CH-10a and CH-12a. An 80 micrograms/ml concentration of HIV peptide was best. Similarities were found by comparing CH-10 peptide with the Organon test kit. The results showed that synthetic HIV-peptide may be a substitute for HIV virus or recombinant HIV antigen for the detection of HIV-antibody in serum.

Enzyme-Linked Immunosorbent Assay↗
PubMed1992

Clear cell odontogenic carcinoma. A case report with massive invasion of neighboring organs and lymph node metastasis.

Clear cell odontogenic carcinoma is a rare and unusual tumor that occurs in the jaws. This tumor is generally considered to be of a low grade of malignancy. We describe a patient with a huge clear cell odontogenic carcinoma that originated in the mandible and exhibited massive invasion into the adjacent tissues and metastases to the submandibular lymph nodes. The ultrastructural and immunohistochemical details are described.

Aged↗
PubMed1992

Multiple folate transport systems in L1210 cells.

Biotin derivatives of methotrexate (biotin-SS-MTX) and folate (biotin-SS-folate), in which the functional components are joined by a dissociable disulfide-containing spacer, have been synthesized, purified by DEAE-Trisacryl chromatography, and characterized by HPLC, elemental analysis and mass spectrometry. These compounds provide a convenient means for the single-step purification of the folate transporters from L1210 cells. Parental L1210 murine leukemia cells, which contain only the microM transporter (the reduced folate/MTX transport protein) were treated with the N-hydroxysulfosuccinimide ester of biotin-SS-MTX, and a detergent extract of the plasma membranes was exposed to streptavidin-agarose beads to adsorb the labeled protein. Dithiothreitol cleavage of the disulfide linkage released the transporter, which migrated as a well-defined component (43 kDa) on SDS-PAGE gels; no other proteins were present. An L1210 subline (JF), obtained by adapting cells to grow on nanomolar concentrations of folate, contains both the microM transporter and the nM transporter (high-affinity folate binding protein). When these cells were treated with the N-hydroxysulfosuccimide ester of biotin-SS-folate and processed as described above, analysis on SDS-PAGE gels revealed the presence of two proteins, the microM transporter (43 kDa) and the nM transporter (39 kDa). Both transporters were characterized with respect to amino acid content; blocked N-termini precluded Edman sequencing. Treatment of the nM transporter with peptide:N-glycosidase F produced a smaller component (32 kDa); the microM transporter, conversely, was unchanged by this procedure. When the microM transporter in parental L1210 cells was labeled with fluorescein-MTX and then treated with phosphoinositol-specific phospholipase C (PI-PLC), no change in fluorescence was detected. Alternatively, when the nM transporter in the JF subline was labeled with fluorescein-folate and then treated with PI-PLC, complete loss of fluorescence was observed. These results indicate that the L1210 microM transporter is a non-glycosylated, integral membrane protein, while its nM counterpart is heavily glycosylated and anchored exofacially to the membrane by a glycosylphosphatidylinositol component.

Animals↗
PubMed1992

Glycogenesis in the cultured fetal and adult rat hepatocyte is differently regulated by medium glucose.

We examined the glycogenic response to glucose in cultured fetal and adult rat hepatocytes. After a 48-h culture in Dulbecco's modified Eagle's medium, 1 mM glucose, insulin, and cortisol, cells were cultured for 4 h in serum-free medium containing glucose (1-30 mM) and U-14C-glucose. Incorporation of 14C-glucose into glycogen was greater in fetal hepatocytes compared with adult hepatocytes at all glucose concentrations (p < 0.001). Net glycogenic rate in fetal cells was greatest between 1 and 8.3 mM (7.7- +/- 1.1-fold increase) compared with a 3.8- +/- 0.6-fold increase in adult cells. In contrast, there was a 19.4- +/- 2.7-fold increase in glycogen accumulated between 8.3 and 30 mM glucose in the adult and a 1.6 +/- 0.1-fold increase in the fetus. Total glycogen synthetase activity was higher in fetal than adult hepatocytes (p < 0.001), but the active a form was similar in fetal and adult hepatocytes. Glycogen synthase a/+b was stimulated at 8.3 mM or greater glucose in fetal hepatocytes, and 5.7 mM or greater in adult hepatocytes (p < 0.05). Total phosphorylase did not change with medium glucose, but glycogen phosphorylase a/a4+b decreased in adult hepatocytes incubated in 5.7 mM glucose or greater (p < 0.05). Fetal phosphorylase a/a+b was increased at 8.3 mM or greater glucose (p < 0.05). In contrast, both adult and fetal phosphorylase were activated by glycogen. A glucose-induced increase in active phosphorylase may induce the decrease in net glycogenic rate at high glucose in fetal hepatocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Pathfinding by cranial nerve VII (facial) motorneurons in the chick hindbrain.

Cranial nerve VII (facial) motorneurons begin extending axons through rhombomeres 4 and 5 (R4 and R5) in the chick hindbrain on the second day of incubation. Without crossing the midline, facial motorneuron axons extend laterally from a ventromedial cell body location. All facial motorneuron axons leave the hindbrain through a discrete exit site in R4. To examine the importance of the exit site in R4 on motorneuron pathfinding, we ablated R4 before motorneuron axonogenesis. We find that mechanisms intrinsic to R5 direct the initial lateral orientation of R5 motorneuron axons. Upon reaching a particular lateral position, all R5 motorneuron axons must turn. In normal embryos the axons all turn rostrally to reach the nerve exit in R4. In embryos with R4 ablated, sometimes the axons turn rostrally and sometimes they turn caudally. A model combining permissive fields and chemotropic cues is presented to account for our observations.

Animals↗