[Study on the determination of trace mercury in foods by circulating enrichment-cold vapour atomic absorption spectrometry]

The determination of trace mercury using the self-developed circulating enrichment apparatus with cold vapour atomic absorption spectrometry was investigated. Various experimental conditions were discussed and optimized. The effect of interferences was examined. The developed method is sensitive, accurate, simple and available and has already been used in the analysis of various kinds of food samples and national standard reference materials, and the results obtained were satisfactory.

[Construction and application of retroviral vector carrying green fluorescent protein]

OBJECTIVE

To construct retroviral vector carrying rapidly selective marker.

METHODS

The recombination retroviral vector GCGFPPXSN was constructed by cloning the green fluorescent protein (GFP) cDNA into the retroviral vector containing putative internal ribosome entry sites GCXPXSN and transferred in ecotropic packaging cell line PE501 by electroporation method. The supernatants of the PE501GCGFPPXSN were used to infect the amphotropic packaging cell line PA317. The G418 resistant clones were selected in 4 weeks and were detectable by fluorescence microscopy or by fluorescence-activated cell sorting(FACS).

RESULTS

A recombination retroviral vector GCGFPPXSN carrying rapidly selective marker GFP was constructed. GFP expression in packaging cell line PA317-GCGFPPXSN transferred by GCGFPPXSN was detected by fluorescence microscopy of FACS. PA317-GCGFPPXSN grew to a titer of 1.2 x 10(5) cpu/ml. By cocultivating retroviral vector producing cells and T lymphocytes, expression of GFP was observed in T lymphocytes 2 days after the end of the cocultivation. T lymphocytes expressing GFP were separated.

CONCLUSION

The mammalian cell can be efficient gene transfected by retroviral vector carrying GFP. The use of GFP for cell marking represents an important advantage over conventional strategies which typically involve the use of neomycin resistance. GFP, in fact, allows a rapid in vitro selection of transduced cell by FACS. The selection requires only two-day culture with this retroviral vector, compared with 10-14 day culture with a classical retroviral vector.

Mapping of Rpb3 and Rpb5 contact sites on two large subunits, Rpb1 and Rpb2, of the RNA polymerase II from fission yeast

[Rpb1 and Rpb2] Mapping of the contact sites on two large subunits of the fission yeast Schizosaccharomyces pombe RNA polymerase II with two small subunits, Rpb3 and Rpb5, was carried out using the two-hybrid screening system in the budding yeast Saccharomyces cerevisiae. Rpb5 was found to interact with any fragment of Rpb1 that contained the region H, which is conserved among the subunit 1 homologues of all RNA polymerases, including the beta' subunit of prokaryotic RNA polymerases. In agreement with the fact that Rpb5 is shared among all three forms of eukaryotic RNA polymerases, the region H of RNA polymerase I subunit 1 (Rpa190) was also found to interact with Rpb5. On the other hand, two-hybrid screening of Rpb2 fragments from RNA polymerase II indicated the presence of an Rpb3 contact site in the region H which is conserved among the subunit 2 homologues of all RNA polymerases, including the beta subunit of prokaryotic RNA polymerases. Possible functions of the regions H in the subunits 1 and 2 are discussed.

[Effects of oxidatively modified lipoproteins on the expression of monocyte chemoattractant protein-1 in endothelial cells]

OBJECTIVE

To clarify whether lipoproteins, particularly oxidatively modified low density lipoprotein (OX-LDL) and very low density lipoprotein (OX-VLDL) play a role in the express of monocyte chemoattractant protein-1 (MCP-1) mRNA and protein in endothelial cells (ECs).

METHODS

After a 24-hour exposure to LDL, OX-LDL, VLDL and OX-VLDL respectively the total RNA in call aorta ECs was extracted by means of guanidinium isothiocyanate method. MCP-1 mRNA expression in ECs was examined by dot blot analysis using a gamma-32P-end-labelled 35 mer oligonucleotide probe of MCP-1. Meanwhile, MCP-1 protein in EC conditioned media (EC-CM) of each group was determined by sandwich ELISA, and MCP-1 protein in ECs was examined immunocytochemically as well.

RESULTS

Cultured calf aorta ECs expressed MCP-1 mRNA and protein, and OX-LDL and OX-VLDL induced further a strong expression of MCP-1 mRNA, and an increased MCP-1 protein level in EC-CM. The expression of MCP-1 mRNA and protein was only slightly increased when exposed to LDL and VLDL, and immunohistological staining with polyclonal MCP-1 antibody give a similar result.

CONCLUSION

OX-LDL and OX-VLDL are able to induce a strong expression of MCP-1 in ECs.

[Study on determination of poisonous heavy metal element lead by graphite furnace atomic absorption spectrometry]

In this paper, the determination of trace lead in foods by optical temperature control GFAAS was studied. The method was certified by the analysis of the national standard reference materials.

Erythrocyte defenses against hydrogen peroxide: the role of ascorbic acid

Ascorbate has been reported to increase intracellular hydrogen peroxide (H2O2) generation in human erythrocytes. In the present work, the basis for this prooxidant effect of the vitamin was investigated in the context of erythrocyte defenses against H2O2. Ascorbate added to erythrocytes caused a dose-dependent increase in intracellular H2O2, which was measured as inactivation of endogenous catalase in the presence of 3-amino-1,2,4-triazole (aminotriazole). Ascorbate-induced catalase inactivation was not observed when only the intracellular ascorbate concentration was increased, when cells were incubated with ascorbate in plasma, or when extracellular Fe3+ was chelated. Together, these results suggest that the observed ascorbate-induced H2O2 generation is due to Fe3+-catalyzed oxidation of extracellular, as opposed to intracellular, ascorbate by molecular oxygen. Rather than generate an oxidant stress in erythrocytes, ascorbate was one of the most sensitive intracellular antioxidants to H2O2 coming from outside the cells. On the other hand, intracellular ascorbate contributed little to the detoxification of H2O2, which was found to be mediated by both catalase and by the GSH system.

Carbohydrates engineered at antibody constant domains can be used for site-specific conjugation of drugs and chelates

To improve the efficiency of site-specific conjugation of chelates and drugs to antibodies, and to minimize the incidence of immunoreactivity perturbation to the resultant immunoconjugates, Asn-linked oligosaccharide moieties were designed and engineered into the constant domains of a humanized anti-CD22 monoclonal antibody, hLL2. From 10 potential glycosylation mutants, two CH1 domain glycosylation sites, HCN1 and HCN5, were identified that were positioned favorably for glycosylation. The carbohydrate (CHO) chains attached at these sites were differentially processed so that HCN5-CHOs were physically larger than HCN1-CHOs. Although both the CH1-appended CHOs, and the LL2 Vkappa-appended CHOs conjugated efficiently with small chelates, the HCN5-CHOs, due to the structural and positional superiority, appear to be a better conjugation site for large drug complexes, such as 18 kDa doxorubicin (DOX)-dextran.

[Perforin and Fas-ligand expression of tumor infiltrating lymphocytes in human hepatocellular carcinoma]

OBJECTIVE

To investigate perforin and Fas-ligand (Fas-L) expression of tumor infiltrating lymphocytes (TIL) in human hepatocellular carcinoma (HCC).

METHODS

Expression of perforin and Fas-L of TIL was studied in 20 HCC cases using in situ hybridization and immunohistochemistry.

RESULTS

Expression of perforin and Fas-L gene were detected in TIL in 80% of the cases studied. Among them, one patient (no. 14) in whom expression of perforin and Fas-L were noticed in the majority of the TIL, had no recurrence of HCC for one and one half (1.5) year after tumor resection. It indicates that presence of large number of activated T cells might be beneficial for the tumor therapy. In the remaining cases, only 10% of TIL were obtained able to express perforin and Fas-L indicating that only a few TIL were activated and cytotoxic to HCC.

CONCLUSIONS

Even there were a multitude of T cells infiltrating in HCC, only few of them were immunoactived and to be cytotoxic to HCC. It seems important to adopt measures in order to promote further proliferation of these activated T cells either in vitro or in vivo.

Interaction of Oct-1 and automodification domain of poly(ADP-ribose) synthetase

We isolated several clones from a matchmaker two-hybrid system human lymphocyte cDNA library using an automodification domain of poly(ADP-ribose) synthetase (PARS) as a probe. A DNA sequence (approximately 1 kbp) of the clone was identical to part of the Oct-1 DNA sequence. We then constructed either a His-tagged or GST fusion protein of the inserted cDNA from the clone and the fusion protein was shown to interact with PARS by far-Western blot analysis and co-precipitation with affinity resin. Furthermore, the His-tagged Oct-1/POU-homeo fusion protein interacted weakly with the octamer motif of the DRa promoter and the addition of PARS fusion protein greatly increased the DNA binding activity. These results suggest that PARS interacts with Oct-1 and stabilizes the binding of Oct-1 to the octamer motif.

Effects of dietary protein and tumor necrosis factor on components of the insulin-like growth factor-I pathway in the colon and small intestine in protein-depleted rats

Intestinal cell growth is markedly affected by nutrient intake and the presence of cytokines. Since insulin-like growth factor-I (IGF-I) is an important hormone regulator of intestinal proliferation, this study examined the effects of dietary protein content and tumor necrosis factor (TNF) on mRNA levels of IGF-I, IGF-I receptor, IGF binding protein-3 (IGFBP-3), and IGFBP-4 and on the histology of the colon, jejunum, and ileum in protein-malnourished rats. After 2 weeks of feeding a 2% casein diet, rats continued on the 2% casein diet or were refed with a 20% casein diet and received daily intraperitoneal injections of either TNF (50 microg/kg) or saline for 4 days. The abundance of mRNA in the intestine was determined by RNA dot-blot analysis, and morphology measurements were performed by light microscopy. Simultaneous refeeding with the 20% casein diet and administration of TNF led to a modest increase in IGF-I and IGFBP-4 mRNA abundance in the colon. However, in the jejunum and ileum, refeeding had no effect but TNF caused a decrease in IGF-I and IGFBP-3 mRNA levels in malnourished rats. Refeeding with the 20% casein diet resulted in relatively modest histologic changes, which were greater in the colon versus the small intestine. The decreased magnitude of histologic changes in the order of the colon, ileum, and jejunum may reflect a response to a gradient of amino acid availability from intraluminal nutrients. These data demonstrate that TNF has distinct effects on colon and small intestine mRNA, but these mild changes had only a slight impact in the colon and did not translate into identifiable histologic changes in the small intestine. Combined protein restriction and TNF administration had only a modest effect on intestinal mRNA levels and mucosal histology.

Effect of continuous enteral medium-chain fatty acid infusion on lipid metabolism in rats

This study compared (i) the relative effects of long-chain triglycerides (LCT) and medium-chain triglycerides (MCT), (ii) the influence of amount of MCT, and (iii) the impact of medium-chain fatty acid position, on plasma and lymphatic triglycerides and portal vein free fatty acids. The animals were fed approximately at 250 kcal/kg.day for 20 h. The lymph from lymphatic duct and blood from portal vein and systemic circulation were collected. The results showed that feeding 100% MCT for 20 h was sufficiently long to reduce significantly the level of linoleic acid in portal vein fatty acids and plasma and lymph triglycerides. However, this alteration induced by MCT feeding was partially prevented by adding LCT to the diet. The level of arachidonic acid was significantly reduced in plasma triglycerides by any of the diets containing medium-chain fatty acids compared to 100% LCT. When feeding MCT only, palmitoleic acid, presumably reflecting de novo lipogenesis, was increased in lymphatic triglycerides and portal vein fatty acids. Total saturated fatty acids as a total percentage of total fatty acids were also significantly increased in plasma and lymphatic triglycerides and portal vein fatty acids. Thus, when linoleic acid is limiting, the conversion of MCT into long-chain fatty acids by de novo lipogenesis is likely to be an important metabolic route. Providing LCT with MCT or 2-monodecanoin appears to limit this pathway.

Comparison of sequences of RNAs 3 and 4 of rice stripe virus from China with those of Japanese isolates

The sequences were determined of RNAs 3 and 4 of a Chinese isolate (Y) of rice stripe tenuivirus (RStV) and were compared with those of two RStV isolates (M and T) from Japan. Both RNAs of the Y isolate were longer than those of the M and T isolates. There was almost complete conservation in the 5' and 3' non-coding regions for each RNA between the isolates. The analogous ambisense coding regions for each isolate were exactly the same size and the sequences were highly conserved. The major differences were in the intergenic regions, the sizes of which accounted for the differences in size of each RNA of the three isolates. There were no obvious patterns of differences in comparisons of the two RNA over the three isolates. The significance of the similarities and differences in sequences of isolates of RStV separated by more than 3500 km is discussed.

[The protective effects of nerve growth factor on peripheral nerve injury]

The protective effects of nerve growth factor (NGF) on peripheral nerve injury and sensory neuron growth were studied in three models: peripheral sympathetic nerve injury induced by intraperitoneal injection of 6-hydrodopamine (6-OHDA), mechanically injured ulnar nerve and cultured dorsal root ganglion (DRG) of newborn rats in vitro. The results indicate that NGF dose-dependently increased norepinephrine content in mouse submandibular gland and cell numbers of C7 (seventh cervical vertebra), T1 (first thoracic vertebra) dorsal root ganglion in rabbits, and also dramatically promoted the growth of neuronal projections in cultured DRG. These results suggest that NGF has significant neuroprotective action in peripheral nerve injury and a strong neuronutrition on sensory neuron.

Synthesis of basic fibroblast growth factor by murine mast cells. Regulation by transforming growth factor beta, tumor necrosis factor alpha, and stem cell factor

BACKGROUND

Mast cells (MC) are involved in a wide spectrum of disorders characterized by neovascularization and fibroproliferation. We and others recently reported that human MC are a source of basic fibroblast growth factor (b FGF-2), a potent angiogenic and mitogenic polypeptide, in several disease conditions, such as chronic inflammation, hemangioma, and benign cutaneous mastocytosis. These findings suggest that FGF-2 may be an important mediator of cell proliferation and angiogenesis associated with MC. Since MC are heterogeneous across species, it is unknown whether FGF-2 expression is a feature common to all MC, or whether FGF-2 expression by MC can be regulated. We therefore examined FGF-2 expression by MC in mouse tissue and MC lines.

METHODS

Immunostaining, RT-PCR, ELISA, immunoblot and Northern blot analyses were employed to study four murine MC lines for FGF-2 expression and its regulation by transforming growth factor-beta (TGF-beta), stem cell factor (SCF), and tumor necrosis factor-alpha (TNF-alpha).

RESULTS

Mouse tissue MC and three of four murine MC lines (CFTL-12, CFTL-15, ABFTL-3) express FGF-2 as judged by immunostaining, ELISA, Western blot and Northern blot analyses, and reverse transcription-polymerase chain reaction. While TNF-alpha appeared to downregulate FGF-2 mRNA levels, treatment with SCF or TGF-beta resulted in an increase in the expression of FGF-2 at mRNA level which can be attenuated by TNF-alpha. However, the concurrent increase in FGF-2 protein was negligible, possibly due to immaturity of these cell lines.

CONCLUSION

Expression of FGF-2 may be a ubiquitous feature of MC in other species in addition to humans, and can be selectively regulated by SCF, TGF-beta and TNF-alpha.

Generation of a high-producing clone of a humanized anti-B-cell lymphoma monoclonal antibody (hLL2)

BACKGROUND

LL2 is a murine immunoglobulin (Ig)G2a-kappa anti-B-cell monoclonal antibody with proven targeting and therapeutic efficacy in the management of non-Hodgkin's lymphoma (NHL). The authors had previously generated a humanized LL2 (hLL2) that demonstrated binding properties identical to those of LL2. Nevertheless, the productivity of the cell line was insufficient for large-scale production of the antibody for clinical studies. Therefore, the authors chose an amplifiable system for the generation of hLL2.

METHODS

The hLL2 sequences were ligated into the expression vector pdHL2, which has a dhfr amplifiable gene, and were incorporated into the SP2/0 cells by electroporation. A methotrexate (MTX) resistant clone producing hLL2 was identified. Stepwise increases in MTX concentrations, from 0.1 to 5 microM, and subcloning of the cells by limiting dilution were performed.

RESULTS

By amplifying the dhfr and hLL2 genes with stepwise increases in the MTX concentration, the antibody production was enhanced from its original 1.4 to 70 +/- 5 mg per liter of culture media. Subsequent subcloning further improved the productivity. Immunoreactivity of the antibody was conserved, as proven by enzyme-linked immunosorbent assay and cell-binding assays. By isoelectrofocusing, the isoelectric point (pI) of the antibody was measured at approximately 9.6. The productivity of the clone was not affected by culture conditions or storage of the cells in liquid nitrogen.

CONCLUSIONS

By means of gene amplification, the authors have generated a high-producing hLL2-IgG clone suitable for production of the quantity of antibody necessary for clinical diagnostic and therapeutic trials of NHL patients.

[The effect of antisense human Fas RNA on activation induced apoptosis of T cell]

OBJECTIVE

To explore an approach to the reduction of activation induced apoptosis of T cell so as to maximize the number of CTL and enhance the tumor cytotoxicity.

METHODS

CD3-induced Jurkat cell line was used as the activated T cell apoptosis model,and the antisense Fas cDNA was introduced into Jurkat cells with retroviral vector.

RESULTS

The expression level of Fas protein in Jurkat cells transducted with the retroviral vector was decreased. Apoptosis was reduced in antisense Fas-transfected Jurkat cells after anti-CD3 or anti-Fas treatment.

CONCLUSION

Antisense blocking of Fas expression can partially inhibit Jurkat cell apoptosis induced by anti-CD3 or anti Fas.

Evidence of an increased number of type IIb muscle fibers in insulin-resistant first-degree relatives of patients with NIDDM

Insulin resistance is a common feature in first-degree relatives of NIDDM patients. To explore the mechanism(s) behind this condition in more detail, a percutaneous muscle biopsy (vastus lateralis) was performed in 25 first-degree relatives of NIDDM patients and 21 control subjects to examine muscle fiber composition and capillary density. Insulin-stimulated glucose disposal (Rd) was determined employing a hyperinsulinemic-(insulin infusion rate 0.6 mU x kg[-1] x min[-1]) euglycemic clamp. Rd (5.76 +/- 0.35 vs. 8.06 +/- 0.36 mg x kg lean body weight [LBW]-1 x min[-], P < 0.001) and estimated VO2max (49.3 +/- 2.8 vs. 57.2 +/- 3.5 mg x kg LBW[-1] x min[-1], 0.05 < P < 0.10) were decreased in the relatives. The number of type IIb fibers (29.5 +/- 2.5 vs. 21.0 +/- 2.8%, P < 0.05) was increased in the relatives, whereas no significant differences were found in other fiber types or capillary density between the groups. Correlations were observed between number of type I fibers (positive), number of type IIb fibers (negative), and capillary density (positive) versus Rd as well as estimated VO2max (P < 0.05). In a multiple linear regression analysis with Rd as a dependent variable, estimated VO2max, family history of NIDDM, and number of type IIb fibers (P < 0.001, r2 = 0.64) significantly determined the level of Rd, whereas capillary density did not. In conclusion, insulin-resistant first-degree relatives of NIDDM patients are characterized by an increased number of type IIb muscle fibers. Whether this finding reflects a reduced physical activity level and fitness in the relatives or is of primary genetic origin remains to be determined.

Type 2 cytokine serum levels in healthy sickle cell disease patients

Sickle cell disease (SCD) is characterized by significant morbidity and early mortality. Children with this hemoglobinopathy exhibit many of the manifestations associated with immunodeficiency disorders. Serum was obtained from 56 healthy SCD subjects and 45 normal healthy controls. Type 2 cytokines interleukin (IL)-4, IL-6, and IL-10 serum levels were measured. Concentrations were determined by reference to a standard curve, and results were expressed in pg/mL. Results revealed significant levels of IL-4 in 6 (13%) of 45 SCD patients compared with 1 (2%) of 45 controls. Increased levels of IL-6 were present in 35 (78%) of 45 SCD patients and 12 (41%) of 29 controls. Elevated levels of IL-10 were detectable in 13 (41%) of 42 SCD patients and 1 (4%) of 25 controls. High circulating levels of type 2 cytokines may suppress both humoral and cell-mediated immune functions in SCD, with resultant increased morbidity.

Action potential duration restitution and electrical excitation propagation in a ring of cardiac cells

The propagation of electrical excitation in a ring of cells described by the Noble, Beeler-Reuter, Luo-Rudy I, and third-order simplified mathematical models is studied using computer simulation. For each of the models it is shown that after transition from steady-state circulation to quasiperiodicity achieved by shortening the ring length (RL), the action potential duration (APD) restitution curve becomes a double-valued function and is located below the original (that of an isolated cell) APD restitution curve. The distributions of APD and diastolic interval along a ring for the entire range of RL corresponding to quasiperiodic oscillations remain periodic with the period slightly different from two RLs. The sigmoidal shape of the original APD restitution curve determines the appearance of the second steady-state circulation region for short RLs. For all the models and the wide variety of their original APD restitution curves, no transition from quasiperiodicity to chaos was observed.

Structure determination of N-linked oligosaccharides engineered at the CH1 domain of humanized LL2

Two humanized antibody mutants, hLL2HCN1 and hLL2HCN5, engineered with CH1 domain-appended carbohydrates (CHOs) were generated to facilitate site-specific conjugation of radionuclides and anti-cancer drugs to antibodies. Such site-specific conjugation may minimize the incidence of immunoreactivity perturbation as is often observed with random conjugation. Since the compositions and structures of CHOs are important in determining the chemistry, efficiency, and extent of conjugation, the sequences of the CH1-appended CHOs were determined by exoglycosidase digestions and fluorophore-assisted CHO electrophoresis (FACE). The CHO species attached at HCN1 and HCN5 sites in hLL2HCN1 and hLL2HCN5, respectively, were distinct from each other, heterogeneous, and extensively processed. All of these CHOs were core-fucosylated complex-type oligosaccharides and contained Gal (galactose) and GlcNAc (N-acetylglucosamine) residues in the outer branches. Some of the outer branches were composed of Gal alpha1-3Galbeta1-4GlcNAc structure, also known as alpha-galactosyl epitope. Most of the CHOs were sialylated. While all HCN1-CHOs were biantennary, the majority of HCN5-CHOs (>60%) were triantennary. The CH1-appended CHOs have favorable structural characteristics suitable for site-specific conjugation. For efficient conjugation of large drug complexes, hLL2HCN5 is preferable to hLL2HCN1 because the attached CHO is larger in size and more remotely positioned from the V region. The effects of the alpha-galactosyl epitope found in these CHOs on the immunological properties of the immunoconjugates as efficient cancer diagnostics and therapeutics are being studied.

Insulin-like growth factor-I improves glucose utilization in tumor necrosis factor-treated rats under hyperinsulinemic-euglycemic conditions

The purpose of this study was to determine the effects of insulin-like growth factor-I (IGF-I) on glucose metabolism in normal and tumor necrosis factor (TNF)-treated rats under euglycemic and hyperinsulinemic conditions. During a hyperinsulinemic clamp (10 mU/kg.min), rats further received either saline or IGF-I (3.33 micrograms/kg.min) infusion for 2 hours. Glucose kinetics were determined with [3H-3]-glucose. Glucose utilization in peripheral tissues was examined by glucose uptake using [14C-2]-deoxyglucose (14C-DG) and by glycogen content in select tissues. The results showed that TNF infusion significantly decreased the rate of glucose infusion required to maintain euglycemia. TNF decreased glycogen content significantly in liver and marginally in abdominis muscle. TNF also decreased glucose uptake in muscle, although the decrease was only statistically significant compared with IGF-I infusion. In addition, TNF significantly reduced plasma IGF-I concentration. However, during hyperinsulinemic and euglycemic conditions, exogenous IGF-I significantly increased glucose uptake in muscle and glycogen storage in the liver and abdominis muscle in both saline- and TNF-treated groups. IGF-I normalized each of the effects of TNF in the rats, including those on plasma IGF-I, glucose uptake in muscle, and glycogen content in liver and abdominis muscle. These data suggest that under hyperinsulinemic and euglycemic conditions, TNF-treated rats, although resistant to insulin, have a normal response to IGF-I, indicating that the TNF-induced defect in the insulin pathway may not be a step in the IGF-I pathway.

Immunolocalization of bFGF in pterygia: association with mast cells

PURPOSE

To examine the expression of basic fibroblast growth factor in pterygia and determine whether mast cells contain basic fibroblast growth factor (bFGF) in this disease process.

METHODS

Formalin-fixed paraffin-embedded tissue samples of pterygia (n = 14) were used to study the expression of bFGF with immunohistochemistry. Seven samples were also double labeled with specific antibodies to bFGF and tryptase (a specific mast cell marker).

RESULTS

In all tissue samples examined, bFGF was specifically localized in blood vessels, epithelium, and a subset of connective tissue cells. The majority of bFGF-positive connective tissue cells were also tryptase positive (90.4 +/- 3.6%). Nearly all the tryptase-positive cells (mast cells) in the pterygia tissues coexpressed bFGF (98 +/- 1.5%).

CONCLUSIONS

These findings suggest that bFGF may have biologic effects on the epithelium and blood vessels in pterygia, with epithelial and endothelial cells as a possible source. In addition, mast cells contain bFGF in the pterygia tissues examined in this study. The mast cells may serve as an additional source of bFGF, possibly modulating a variety of cell types as well as the extracellular matrix in pterygia.

In vitro suppression of the normal mitogenic T lymphocyte response by steady state sickle cell disease sera

This study is part of a long term evaluation of sickle cell disease (SCD) as a paradigm for immunosuppression. Serum was obtained from 43 SCD patients during the steady (healthy) state. Peripheral blood mononuclear cells (PBMC), separated by density gradient were obtained from 8 normal healthy donors. PBMC were utilized in assays directly or as a source for obtaining, total T (CD3) and helper T (CD4) cell populations separated by specific T cell columns. Standard in vitro phytohemagglutinin (PHA) stimulation of lymphocyte cultures was done with culture media containing 10% SCD serum, as compared to normal pooled O, Rh+ (O+) serum. Mitogenic responses were expressed as mean counts per minute (cpm) and stimulation index of triplicate cultures. Results revealed PHA responses were positive in all experiments when a standard stimulation index of 10 or greater was used as a test parameter for comparison. Positive results were demonstrated in 43/43 (100%) of triplicate cultures regardless of serum type in all experiments. Conversely, by using mean cpm as the test criterion, suppression of PHA response was shown in SCD serum supplemented cells as follow; 36/43 (84%) of PBMC, 35/43 (81%) of CD3 and 37/43 (86%) of CD4 cultures. The degree of suppression ranged from > 10% to 98% in individual experiments, as compared to O+ serum. Inhibitors of normal T lymphocyte in vitro PHA response appear to be present in a significant percentage of SCD sera even during the healthy state of disease. Type 2 cytokines which suppress cell mediated immunity would seem to be the most likely inhibitory agents.

Tissue-specific effects of chronic dietary protein restriction and gastrostomy on the insulin-like growth factor-I pathway in the liver and colon of adult rats

Dietary protein restriction decreases plasma concentrations of insulin-like growth factor-I (IGF-I) and reduces IGF-I mRNA levels in the liver. In addition to the actions of systemic IGF-I, locally produced IGF-I is thought to mediate autocrine and paracrine growth effects in the colon. The objectives of the present study were to investigate the IGF-I pathway in the colon and liver of adult rats under conditions of dietary protein restriction, surgical stress, and dietary protein repletion. Two groups of rats were placed on either a 20% or 2% casein diet for 19 days. Two additional groups of rats underwent gastrostomy after a 2% casein diet for 2 weeks, and then were either kept on the 2% casein diet or changed to a 20% casein diet until day 19. Dietary protein restriction reduced plasma concentrations of IGF-I and IGF-binding proteins (IGFBPs) and hepatic IGF-I mRNA content, while increasing colonic IGF-I receptor mRNA. Gastrostomy in protein-depleted animals had no effect on hepatic IGF-I mRNA, but led to a marked increase in colonic IGF-I mRNA levels. Dietary protein repletion resulted in a decrease in colonic IGF-I receptor mRNA. The distinct effects of dietary protein depletion and operative stress on the IGF pathway in the colon as compared with the liver may serve to maintain the level of IGF-I signaling in the colon by autocrine or paracrine mechanisms under these conditions.

[Expression of ICAM-1 mRNA in HCC using in situ hybridization technique]

OBJECTIVE

To study the relationship between the intercellular adhesion molecule 1 (ICAM-1) mRNA expression of hepatocellular carcinoma (HCC) and its invasion and metastasis.

METHODS

34 cases of HCC and their pericarcinomatous tissues were studied on cryostat sections by in situ hybridization to investigate ICAM-1 mRNA expression.

RESULTS

The ICAM-1 mRNA expression was stronger in the carcinomatous tissues of 19/21 invasive cases than that in the pericarcinomatous tissues, while in the 13 non-invasive cases, only 4 exhibited weak ICAM-1 mRNA expression.

CONCLUSION

ICAM-1 mRNA expression may correlate with increased risk of invasion and metastasis of HCC.

[Effects of oxidatively modified low density lipoprotein and very low density lipoprotein on the expression of MCP-1 in macrophages]

OBJECTIVE

To examine whether oxidatively modified low density lipoprotein (OX-VLDL) and very low density lipoprotein (OX-VLDL) induce the expression of MCP-1 mRNA and protein by rabbit peritoneal exudate macrophages, and to clarify what a role of both lipoproteins play in atherogenesis.

METHODS

After exposure of the macrophages to 25 micrograms/ml of LDL, VLDL, OX-LDL and OX-VLDL respectively, and a 24 hour incubation at 37 degrees C, the total RNA was extracted from the cells by guanidinium isothiocyanate method, and the media conditioned by the cultured macrophages were collected. Meanwhile, MCP-1 protein in the conditioned media was determined by using sandwich ELISA. Monocyte migration induced by the media was assayed by micropore filter method using modified Boyden chamber.

RESULTS

After a 24 hour exposure to OX-LDL and OX-VLDL, the MCP-1 mRNA expression in macrophages was markedly increased (3.2-fold and 3.4-fold, respectively), and the level of MCP-1 protein was also increased (2.2-fold and 2.5-fold, separately), and furthermore, the monocyte migration distance was significantly increased. However, the expression of MCP-1 mRNA and protein was only slightly increased when exposed to LDL or VLDL.

CONCLUSIONS

Rabbit peritoneal exudate macrophages can express MCP-1 mRNA and protein, and OX-LDL and OX-VLDL induce stronger MCP-1 mRNA and protein expression in the cells.

Correlation between HLA-DR expression and level of poly(ADP-ribose) synthetase in human thyroid carcinoma cells

The expression of MHC class II molecules is normally restricted to antigen presenting cells. Aberrant expression of class II molecules, however, was detected in the thyrocytes of autoimmune thyroid diseases. We attempted to regulate the expression of HLA-DR molecules in thyroid carcinoma cells by expressing the exogenous poly(ADP-ribose) synthetase gene. We transfected a metal inducible expression plasmid capable of expressing poly(ADP-ribose) synthetase gene into thyroid carcinoma 8505C cells and the transformants, treated with metal and IFN-gamma, were separated by Magnetic Cell Separation. The activity of the synthetase was increased in the HLA-DR-enriched transformants as compared with that in control or the HLA-DR+ transformants. RNA blot analysis and flow cytometric analysis revealed that the IFN-gamma-inducible expression of HLA-DR molecules was depressed by the induction of exogenous poly(ADP-ribose) synthetase gene. This result indicates that HLA-DR expression was correlated with the level of poly(ADP-ribose) synthetase in human thyroid carcinoma cells. Furthermore we examined the level of poly(ADP-ribose) synthetase in patients with autoimmune thyroid diseases. We observed a significant decrease in poly(ADP-ribose) synthetase in the patients. Taken together with the previous observation, the decrease in poly(ADP-ribose) synthetase is closely linked to the aberrant expression of HLA-DR molecules in some autoimmune thyroid diseases.

Immunologic effects of acute hyperglycemia in nondiabetic rats

BACKGROUND

This study was designed to determine the consequences of acute hyperglycemia on the immune function of peripheral neutrophils, peritoneal macrophages, and alveolar macrophages in nondiabetic rats.

METHODS

The animals were randomly divided into nonsurgical (normal) and surgical groups. The postoperative rats were further divided into normoglycemic (control) and hyperglycemic (glucose) groups. The hyperglycemic condition was maintained by constant infusion of glucose to raise plasma glucose concentration to 300 mg/dL for 3 hours. The immune cells were then harvested to determine their phagocytic and oxidative capacities via flow cytometry.

RESULTS

The results showed that hyperglycemia significantly decreased the respiratory burst of alveolar macrophages (p < .05). In contrast, hyperglycemia enhanced phagocytosis in these cells (p < .002). There was a significant activation of the respiratory burst in peripheral neutrophils by surgery (p < .002), but no effect of hyperglycemia.

CONCLUSIONS

We conclude that hyperglycemia itself can influence immune function in some phagocytic cells, which may be an important factor in postsurgical infection.

Visualisation of capillaries in human skeletal muscle

A double staining method combining Ulex europaeus agglutinin I lectin (UEA-I) and collagen type IV staining was used to determine the capillary density and the number of capillaries relative to different fibre types in human skeletal muscles. The result of this combined staining was compared with that of other staining methods including amylase-periodic acid Schiff (PAS), UEA-I, anti-collagen type IV and anti-von Willebrand factor. Muscle biopsy specimens, 12 from M. vastus lateralis and 6 from M. soleus, were obtained from 18 healthy young men. Compared with amylase-PAS staining, double staining showed a larger number of capillaries surrounding type I (+9.6%), type IIA (+8.6%) and type IIB (+11.6%) fibres in the M. vastus lateralis specimens (P < 0.001 for all differences). The capillary to fibre ratio (cap fibre-1) and the capillary density (cap.mm-2) were 8.3% (P < 0.002) and 7.9% (P < 0.001) larger, respectively. In the M. soleus specimens, cap.fibre-1 and cap.mm-2 were 7.4 and 9.9% larger, respectively, by double staining compared with PAS staining. Further comparisons showed that the cap.fibre-1 and cap.mm-2 obtained with double staining were similar to the values determined by the UEA-I staining, but greater than that measured by the collagen type IV method. The double staining gave a more marked stain of capillaries and revealed muscle fibre borders clearly, which is an advantage in studies that require comparisons between serial sections using computerised image analyses. It is concluded that the double staining method is superior to either the UEA-I, collagen type IV or the traditional amylase-PAS staining methods in analysing capillary density of normal human skeletal muscle.

Efficient gene expression in mammalian clock pacemaker cell in vitro by an adenovirus vector

An efficient modified adeno system to express foreign genes to the central nervous system was developed recently. This modified recombinant adenoviral vectors can be used successfully to deliver lacZ to the hypothalamic suprachiasmatic nucleus (SCN) which is composed of mammalian clock pacemaker. The expression of lacZ in the primary culture of SCN was dose-dependent and higher enough in nearly 100% of these cells. We also showed that viral toxicity and lacZ overexpression had no serious effects on the rhythmic expression of arginine vasopressin (AVP) release from the SCN cell culture.

Altered immunohistochemical localization of basic fibroblast growth factor after bleomycin-induced lung injury

Basic fibroblast growth factor (bFGF) is a potent inducer of growth and proliferation for many cell types involved in wound healing. Although bFGF has previously been identified in lung tissue, its role in the pathogenesis of pulmonary fibrosis is unknown. We investigated the distribution of bFGF after bleomycin-induced lung injury in the rat in hope of learning how bFGF might participate in the process of lung injury, repair and fibrosis. Increased immunoreactive bFGF was found in the extracellular matrix after bleomycin and co-localized to a marker of active cell proliferation. This suggests that bFGF may participate in directing cell proliferation following lung injury. In addition, a marked increase in the number of mast cells with strong reactivity for bFGF was found at days 14 and 21 after bleomycin. These cells may represent a source of bFGF during the fibroproliferative stage after lung injury.

Role of interferons in demyelinating diseases

IFN beta-1b reduces the frequency of major multiple sclerosis attacks by 50 percent. Serial MRI scanning over the course of the clinical trial that led to approval of the agent revealed a significant lessening both in disease activity and in accumulating burden of disease in IFN beta-1b-treated patients compared to placebo-treated controls. The mechanism by which IFN beta-1b exerts its beneficial effect in multiple sclerosis is unknown. T suppressor cell function fails during MS attacks and is persistently subnormal in multiple sclerosis patients with progressive disease. IFN beta-1b partially restores suppressor function in multiple sclerosis patients. IFN beta-1b also inhibits release of lymphotoxin, tumor necrosis factor, and interferon gamma, at least in vitro. All three cytokines are toxic to oligodendrocytes. In contrast; production of transforming growth factor beta-1 (TGF beta 1) is increased by IFN beta-1b. TGF beta 1 is an immunosuppressive cytokine. All of the above listed actions of IFN beta-1b could contribute to its beneficial effect. Perhaps all do.

Determinants of plasma concentrations of insulin-like growth factor-I and albumin and their hepatic mRNAs: the role of dietary protein content and tumor necrosis factor in malnourished rats

Protein restriction decreases plasma concentrations of albumin and insulin-like growth factor-I (IGF-I) by reducing their hepatic mRNA levels, whereas protein restriction increases IGF-I binding protein-2 (IGFBP-2) gene expression in the liver. Tumor necrosis factor (TNF), as an inducer of the injury response, decreases plasma albumin concentration and albumin mRNA in the liver. The present study was designed to evaluate the effects of protein repletion and TNF on plasma albumin and IGF-I and their mRNAs and IGFBP-2 mRNA in the liver of protein-restricted rats. After 2 weeks of feeding a 2% casein diet, rats were assigned to four groups according to either being refed with a 2% or 20% casein diet or receiving saline or TNF by intraperitoneal injection (50 microg/kg x d) for 4 days. Plasma IGF-I and albumin were assayed. Hepatic mRNAs of IGF-I, albumin, and IGFBP-2 were determined. Protein repletion increased plasma concentrations of IGF-I and albumin and their mRNA content in the liver, but decreased IGFBP-2 mRNA. TNF did not alter plasma IGF-I concentration but did increase hepatic IGF-I mRNA in protein-repleted animals, and plasma albumin concentration was significantly decreased with unaltered hepatic albumin mRNA. Thus, protein repletion of malnourished rats increased plasma IGF-I and albumin concentrations in association with increased expression of their mRNAs in the liver. However, plasma albumin but not IGF-I decreased following TNF in protein-restricted rats, whereas TNF increased hepatic IGF-I mRNA in protein-repleted rats. Thus, only plasma albumin concentration responds to both principal determinants, diet and injury, in the development of malnutrition.

[Effects of oxidized low density lipoprotein and very low density lipoprotein on the expression of MCP-1 by monocytes]

Monocyte chemoattractant protein-1 (MCP-1) is a potent chemotatic factor for monocytes. This study aimed at examination of the effects of oxidized low density lipoprotein (OX-LDL) and oxidized very low density lipoprotein (OX-VLDL) on the expression of MCP-1 mRNA and protein by monocytes. The guanidinium isothiocyanate method was used to extract total RNA from monocytes which were exposed to LDL, OX-LDL, VLDL and OX-VLDL for 24 hours respectively and the monocyte derived conditioned media collected. MCP-1 mRNA expression in monocytes was examined by slot blot and Northern blot analysis using a gamma 32P-end-labelled 35 mer oligonucleotide probe of MCP-1. Meanwhile, MCP-1 protein in the conditioned media was examined by use of sandwich ELISA. It was found that monocytes from human peripheral blood can express MCP-1 mRNA and protein after 24 hours incubation at 37 degrees C and the expression of MCP-1 mRNA and protein was markedly increased by a 24 hour exposure to OX-LDL and OX-VLDL, whereas the expression of MCP-1 mRNA and protein was only sightly increased when exposed to LDL and VLDL. It is concluded that monocytes can express MCP-1 that induce additional monocyte migration into the subendothelial space, and that OX-LDL and OX-VLDL enhance this function by inducing stronger MCP-1 expression in monocytes.

[Protective effects of radix Salviae miltiorrhizae on azathioprine hepatotoxicity in rats]

The changes of liver function and malondialdehyde (MDA) and glutathione (GSH) were studied in rats intoxicated with azathioprine (Aza) 15mg/(kg.d) and in rats treated with Aza mixed Salviae 8g/(kg.d). The results showed that in the Aza group, the levels of ALT, AKP, MDA increased and GSH decreased significantly in week 1 and week 2. But in the Salviae group the levels of ALT, AKP, MDA decreased and GSH increased significantly, approaching the normal levels, It follows that Salviae has protective effects on Aza hepatotoxicity in rats.

The synapse-associated protein rapsyn regulates tyrosine phosphorylation of proteins colocalized at nicotinic acetylcholine receptor clusters

Protein tyrosine phosphorylation has been suggested to play an important role in the clustering of the nicotinic acetylcholine receptor (AChR) at the developing neuromuscular junction. Recent studies have shown that the 43-kDa synapse-associated protein rapsyn induces clustering of the AChR in heterologous expression systems. In this study we examined whether tyrosine phosphorylation is involved in this rapsyn-induced AChR clustering. Rapsyn-induced AChR clusters in fibroblasts contain phosphotyrosine, as detected using immunofluorescent labeling with anti-phosphotyrosine antibodies. No anti-phosphotyrosine staining of rapsyn clusters is seen in the absence of AChR expression, indicating that the AChR is required for the appearance of phosphotyrosine at clusters. In addition, coexpression of rapsyn with the AChR induces the tyrosine phosphorylation of the beta amd delta subunits of the AChR. Surprisingly, mutation of the tyrosine phosphorylation sites in the AChR did not inhibit rapsyn-induced clustering of the AChR and clusters of the mutant AChRs still contained high levels of phosphotyrosine. Experiments with single AChR subunits demonstrate that the alpha subunit of the AChR appears to be necessary and sufficient for codistribution of phosphotyrosine with rapsyn-induced clusters of AChR subunits. Finally, transfection of cells with rapsyn activates cellular protein tyrosine kinase activity, resulting in the tyrosine phosphorylation of several membrane-associated proteins. These results suggest that rapsyn may therefore regulate clustering at least in part by regulating the tyrosine phosphorylation of cellular proteins.

Characterization of the murine antibody response to peptides representing the variable domains of the major outer membrane protein of Chlamydia pneumoniae

In an attempt to gain more knowledge about the immunogenicity of the variable domains (VDs) of the major outer membrane protein (MOMP) of Chlamydia pneumoniae, peptides representing these areas were used to immunize BALB/c and C57BL/6 mice. Antisera to the peptides and to peptides conjugated to keyhole limpet hemocyanin (KLH) were characterized by their ability to recognize the immunizing peptide and elementary bodies (EBs) of C. pneumoniae by enzyme-linked immunosorbent assay (ELISA) and Western blot (immunoblot). In addition, antiserum was analyzed for its molecular specificity by a pepscan as well as its in vitro neutralizing ability. In general, results obtained with antisera to the peptides paralleled the results obtained with the antisera to the KLH-conjugated peptides except that the titers or strength of reaction in the assays was less. Antisera to the VDs in both strains of mice gave ELISA titers to the homologous VD peptide ranging from 1,000 to >64,000. The strength of reactivity with the reduced MOMP as judged by Western blot, in most cases, paralleled the ELISA titer to the peptide. However, only antisera raised in both strains of mice to the VD1 and VD4 peptides reacted strongly with the EBs, suggesting surface exposure of these VDs. In addition, antisera to VD3 from C57BL/6 mice gave strong reactivity to EBs. By pepscan analysis antisera from both strains of mice reacted with several VD1 and VD3 octameric peptides, with weaker reactivity being seen with the octameric peptides in the other two VDs. This was in contrast to antisera raised to EBs of C. pneumoniae TW-183, which identified two immunogenic regions, one in VD1 and the other mapped to VD4. While antisera raised to EBs strongly neutralized the infectivity of C. pneumoniae, none of the peptide antisera was able to neutralize. In addition, peptides to the VDs were not able to block the neutralizing ability of the antisera to EBs of C. pneumoniae. Therefore, these results suggest that the VDs of the MOMP of C. pneumoniae are surface exposed but do not elicit neutralizing antibodies when linear peptides representing them are used as the immunogen.

Growth hormone stimulates tyrosine phosphorylation of JAK2 and STAT5, but not insulin receptor substrate-1 or SHC proteins in liver and skeletal muscle of normal rats in vivo

GH has been shown to stimulate tyrosine phosphorylation of JAK2, several STAT proteins, insulin receptor substrate-1 (IRS-1), and SHC proteins in cultured cells. The goal of this study was to determine GH effects on protein tyrosine phosphorylation in liver and skeletal muscle of normal rats in vivo. Nonfasted male Sprague-Dawley rats (225-250 g) were injected with GH iv, and tissues were obtained after 5, 15, 30, or 60 min. At a maximally effective GH dose (1.5 mg/kg body weight), phosphotyrosine antibody immunoblots demonstrated marked stimulation of the tyrosine phosphorylation of JAK2 (maximal at 5 min) and a 95,000 Mr protein (maximal at 15 min) in both liver and skeletal muscle. The 95,000 Mr protein was recognized and immunodepleted by STAT5 antibody, but not by other STAT protein antibodies. Although basal tyrosine phosphorylation of IRS-1 and SHC was evident, GH did not stimulate tyrosine phosphorylation of either of these proteins in liver or skeletal muscle. In conclusion, GH stimulates the tyrosine phosphorylation of JAK2 and STAT5, but not IRS-1, SHC, or other STAT proteins in liver and skeletal muscle of normal rats. These results differ from findings in cultured cells and support the concept that selectivity for tyrosine kinase substrates is an important determinant of postreceptor signaling specificity in vivo.

[Experimental study on delayed effect of external skin expansion]

In using the external skin expander, we found that the expanded skin had the feature similar to a delayed flap. To study its mechanism, we chose 20 New Zealand rabbits and divided them into 2 groups randomly. The skin on the animal's back in the experimental group was expanded with the external skin expander. The laser Doppler flowmeter (LDF) and oxyhemograph (SpO2) were applied to detect skin microcirculation. The survival area and the results of microangiography of the two groups were compared. Results showed that the value of LDF of the expanded skin increased and the value of SpO2 returned to its origingal level at 12 days after expansion. The survival area in the experimental group was larger than the control. Microangiographic examinations indicated that the subcutaneous vascular anastomoses were obviously increased in the experimental group. We conclude that external skin expansion does not affect the quality of the expanded skin, and its effect is similar to delay technique.

Protein and lipid refeeding changes protein metabolism and colonic but not small intestinal morphology in protein-depleted rats

In this study, we fed rats a 2% casein AIN 76 diet for 2 wk to produce protein malnutrition. We determined in these animals the effects of different concentrations of dietary protein refeeding (2% and 20% casein) on recovery and gut mucosal repletion and the potential role of type of dietary fat in the regulation of protein metabolism and mucosal growth by providing conventional long-chain triglyceride (LCT), a structured lipid composed of long-, medium- and short-chain fatty acids (SC/SL), or a physical mixture of the same components present in the structured lipid given as individual pure triglycerides (SC/PM) along with adequate amounts of protein and energy. The results confirmed that protein malnutrition can be reversed rapidly by protein refeeding, as indicated by an increase in body weight, positive nitrogen balance, liver growth and elevations in plasma concentrations of insulin-like growth factor-1, leucine and albumin. In the colon, crypt cell number, crypt depth and number of crypt cells in the rapidly proliferating fraction of the colon were greater in rats fed the higher protein diet. However, the general architecture of small intestinal mucosa, including duodenum, jejunum and ileum, was not affected by protein malnutrition. Although the number of colonic cells was similar with fat refeeding, there were significantly fewer displaying the proliferating cell nuclear antigen in the colonic epithelium when rats were fed SC/PM compared with SC/SL. Therefore, changes in colonic mucosal proliferation were only seen with repletion by adequate protein and by SC/SL feeding.

The effect of orientation within a chimeric peptide on the immunogenicity of Chlamydia trachomatis epitopes

Peptides representing the Chlamydia trachomatis major outer membrane protein variable domains (VD) 1 and 4 of serovars C and E, respectively, have been shown to elicit a neutralizing antibody response in mice. To assess whether the position within a chimeric peptide influences the immunogenicity of the epitopes, two constructs, VD 1-4 and VD 4-1, were made in which the position of the VD relative to the amino and carboxy terminals were rotated. C57BL/10 mice were immunized with 100 micrograms of peptide in complete Freund's adjuvant (FA) on day 0, followed by an immunization with peptide (100 micrograms) in complete FA on day 14. By day 21 the immunodominant epitope in both chimeras as measured by ELISA was the one located at the carboxy terminus. A pepscan of the VD 1-4 antisera revealed a main peak in VD 4 which had been previously identified by neutralizing MAbs. The VD 4-1 antisera gave a peak in the VD 1 region which did not correspond to regions previously mapped with neutralizing MAbs. The VD 1-4 antisera but not the VD 4-1 antisera was able to neutralize in vitro serovar E. In summary, the position of these chlamydial epitopes within a chimeric peptide greatly influenced the resulting immune response.

Partial purification of smooth muscle cell derived growth factor

The serum free medium conditioned by cultured rabbit aortic smooth muscle cells was partially purified using ultrafiltration and heparin affinity chromatography. Incorporation of [3H]-thymidine (3H-TdR) into cell DNA was used to measure the mitogenic activity of the fractions from chromatography for NIH 3T3 fibroblasts. The molecular weight and the iso-electric point of these fractions were determined by NaDodSO4-polyacrylamide gel electrophoresis (SDS-PAGE) and iso-electric focusing, respectively. The results showed that the protein eluted in 1.0-1.6 mol/L NaCl from the heparin-Sepharose was mitogenic for 3T3 cells, and this protein had a molecular weight of 22.8-26.7 ku and an iso-electric point of about 4.6. The fact that the above-mentioned biochemical properties differed from that of PDGF, IGF and FGF suggests that this mitogenic protein may be a separate growth factor.

Mast cells are a major source of basic fibroblast growth factor in chronic inflammation and cutaneous hemangioma

Mast cells play an essential role during development of inflammation after chemical and immunological insults and have been implicated in tissue fibrosis and angiogenesis. The exact contribution of mast cells to these conditions is largely unknown. In this study, we found that a potent angiogenic and mitogenic polypeptide, basic fibroblast growth factor (bFGF), is localized to the majority of mast cells from normal skin and lung and in tissue samples characterized by fibrosis, hyperplasia, and neovascularization. Using specific antibodies to mast cell tryptase, tissue macrophage, and bFGF, we demonstrate that cytoplasmic bFGF immunoreactivity is localized to 96.8 +/- 9.6% of tryptase-positive cells in human fibrotic lung tissue (n = 10), 82.3 +/- 6.9% of tryptase-positive cells in rheumatoid synovia (n = 6), and 93.1 +/- 4.8% of tryptase-positive cells in skin hemangioma (n = 5). Moreover, these tryptase-positive cells comprise a major portion (86 to 97%) of nonvascular cells exhibiting cytoplasmic bFGF staining in these tissues. In contrast, macrophage-like cells contribute less than 10% of the bFGF-positive cells in the same samples. The specificity of the immunostaining results was supported by the finding that cultured human mast cells (HMC-1) express both bFGF mRNA and protein. Our data indicate that mast cells, a primary source of heparin, also serve as a significant source of a heparin-binding growth factor, bFGF, in these disease processes. These observations suggest that mast cells may contribute to these pathological conditions by releasing this polypeptide.

Expression of basic fibroblast growth factor in synovial tissue from patients with rheumatoid arthritis and degenerative joint disease

BACKGROUND

Recent studies have implicated polypeptide growth factors in the development of rheumatoid arthritis (RA), which is characterized by synoviocyte hyperplasia and neovascularization. One such polypeptide, basic fibroblast growth factor (bFGF), is of particular interest because of its potent mitogenic and angiogenic activities. We have previously reported that cultured human synoviocytes synthesize and bind bFGF and also proliferate in response to it (1). Recently, we found a close association between increased bFGF expression and destructive changes in arthritic joints from rats (2). Now we extend our study by detecting in vivo expression of bFGF in human synovial tissues obtained from patients with RA.

EXPERIMENTAL DESIGN

Human synovial tissues from patients with RA, degenerative joint disease (DJD), and trauma were collected during joint surgery. The expression of bFGF protein and mRNA by the synovia was examined by immunolocalization, Western blot, Northern blot, and RNase protection assays. Synovium from patients with DJD and trauma was used to compare with rheumatoid synovium. Double immunostaining with cell type-specific antibodies was carried out to identify cellular sources of bFGF.

RESULTS

Both polypeptide and mRNA for bFGF were detected in the synovial samples examined. Increased bFGF staining was found in synovium-cartilage interface where joint destruction occurred and in hyperplastic synoviocytes of a subset of rheumatoid synovium. Strong cytoplasmic bFGF staining was localized in the majority of mast cells and vascular cells.

CONCLUSIONS

Synovial tissue from patients with RA, DJD, and trauma express bFGF. Increased bFGF staining in the hyperplastic lining synoviocytes and at the pannus-cartilage interface suggests that bFGF may play a role in synovial hyperplasia and joint destruction. Strong cytoplasmic bFGF staining found in mast cells and vascular cells indicates that these cells are the major sources of tissue bFGF.

Phosphorylation of the nicotinic acetylcholine receptor by protein tyrosine kinases

Most neurotransmitter receptors examined to date are either regulated by phosphorylation or contain consensus sequences for phosphorylation by protein kinases. The nicotinic acetylcholine receptor (AChR), which mediates depolarization at the neuromuscular junction, has served as a model for the study of the structure, function, and regulation of ligand-gated ion channels. The AChR is phosphorylated by protein kinase A, protein kinase C, and an unidentified protein tyrosine kinase. Tyrosine phosphorylation of the AChR is correlated with a modulation of the rate of receptor desensitization and is associated with AChR clustering. We showed that agrin, a neuronally derived extracellular matrix protein, induces AChR clustering and tyrosine phosphorylation. In addition, we identified two protein tyrosine kinases, Fyn and Fyk, that appear to be involved in the regulation of synaptic transmission at the neuromuscular junction by phosphorylating the AChR. The two kinases are highly expressed in Torpedo electric organ, a tissue enriched in synaptic components including the AChR. As demonstrated by coimmunoprecipitation, Fyn and Fyk associate with the AChR. Furthermore, the AChR is phosphorylated in Fyn and Fyk immunoprecipitates. We investigated the molecular basis for the association of the AChR with Fyn and Fyk using fusion proteins derived from the kinases. The AChR bound specifically to the SH2 domain fusion proteins of Fyn and Fyk. The association of the AChR with the SH2 domains is dependent on the state of AChR tyrosine phosphorylation and is mediated by the delta subunit of the receptor. These data provide evidence that the protein tyrosine kinases Fyn and Fyk may act to phosphorylate the AChR in vivo.