[Studies on anti-inflammatory and immune effects of moxibustion]

An animal model of adjuvant arthritis in rats was established, and the effects of anti-inflammatory and immune regulation of moxibustion at "Shenshu" point were investigated. The results showed that it could lighten a local inflammatory reaction, eliminate swelling of the metatarsal and reduce it's girth, prevent or reduce the polyarthritises, maintain the weight and shorten the course of the disease. The results also showed that moxibustion could recover and promote the effects of the Concanavalin A (ConA) inducing splenic lymphocyte proliferation in rats, promote interleukin 2 (IL-2) production, decrease IL-1 contents. The indexes mentioned above were significantly different as compared with contral group. Above results indicated that moxibustion had directly anti-inflammatory and subsidence of swelling effects, through enhancing the ability of immune response the immune functions were lightened and regulated. Therefore, the anti-inflammatory and immune and anti-allergy effects of body were enhanced.

Thermal relations of metabolic rate reduction in a hibernating marsupial

We tested whether the reduction of metabolic rate (MR) in hibernating Cercartetus nanus (Marsupialia, 36 g) is better explained by the reduction of body temperature (Tb), the differential (delta T) between Tb and air temperature (Ta), or thermal conductance (C). Above the critical Ta during torpor (Ttc) of 4.8 +/- 0.7 degrees C where the Tb was not regulated, the steady-state MR was an exponential function of Tb (r2 = 0.92), and the overall Q10 was 3.3. However, larger Q10 values were observed at high Tb values during torpor, particularly within the thermoneutral zone (Q10 = 9.5), whereas low Q10 values were observed below Tb 20 degrees C (Q10 = 1.9). The delta T did not change over Ta 5-20 degrees C, although MR fell, and therefore the two variables were not correlated. Below the Ttc, Tb was regulated at 6.1 +/- 1.0 degrees C and MR increased proportionally to delta T. Our study suggests that MR in torpid C. nanus is largely determined by temperature effects and metabolic inhibition. In contrast, delta T explains MR only below the Ttc and C appears to affect MR only indirectly via changes of Tb, suggesting that delta T and C play only a secondary role in MR reduction during hibernation.

Elevation of protein kinase C in thyrocytes isolated from a Lewis rat model of autoimmune thyroiditis prevents assembly of immunodetectable connexin43 gap junctions and reduces intercellular communication

In the Lewis rat model of experimental autoimmune thyroiditis (EAT), decreased immunodetectable connexin assembly into gap junctions and diminished intercellular communication are associated with the loss of thyroid function (hypothyroidism) that occurs prior to significant tissue destruction. The current study explores the hypothesis that the loss of connexin 43 (Cx43)-mediated intercellular communication in these cells is caused by upregulation of protein kinase C (pKC) activity. Thyrocytes isolated from EAT rats exhibited a 78% increase in basal pKC activity; whereas, basal protein kinase A (pKA) activity was unchanged. Increased pKC activity was a result of increased isozyme protein levels. Thyroid cells expressed pKC isozymes gamma and lambda and had elevated levels of alpha (40%), beta (30%), delta (31%), and epsilon (25%) as quantified by western blot analyses. Furthermore, modulation of pKC activity inversely altered Cx43 assembly and function in monolayer thyrocytes. For example, octoacetyl glycerol (OAG) treatment of normal thyrocyte monolayers to increase pKC activity resulted in deficient Cx43 gap junction assembly and reduced intercellular communication indistinguishable from the deficits in EAT thyrocytes. Conversely, calphostin C inhibition of pKC activity in EAT thyrocyte monolayers restored these parameters to normal. Thus, pharmacological modulations of pKC activity in cultured thyrocytes support a causal relation between the changes in pKC activity and Cx43-mediated intercellular communication. Abnormalities in autoimmune diseased thyroid tissue (eg, increased pKC) appear to contribute to reduced intercellular coordination of thyroid follicles and thereby can affect subsequent thyroid function. The persistence of target cell abnormalities in the absence of infiltrating lymphocytes and their products supports an alternative mechanism by which thyroid function can be affected that does not depend on the loss of thyroid glandular epithelium.

[Image analysis of the microvascular permeability to various molecular weight of flucrescein in rat mesentery]

An intravital fluorescence microscopic method and digital image analysis were established for measuring the changes of fluorescein sodium (FINa, MW 376) and FITC-Dextrans (FD-4, MW4000, FD-150, MW150000) permeability in mesenteric microvessels. The transport of various molecular fluorescent tracer within the blood vessels and through the vessel walls into the perivascular tissue of the rat mesentery was studied using a highly sensitive CCD camera, the fluorescence intensities were transformed into video signals and recorded for subsequent analysis. The results showed that FINa could pass through the wall of microvessels very quickly. The diffusion constant was 3.362 x 10(-8) cm2/s with FINa, and FD-4 was 1.718 x 10(-8) cm2/s, FD-150 was 0.0486 x 10(-8) cm2/s. The diffusion constant depended very strongly on the molecular weight and showed no difference between capillary and vessels of the venous part of the microcirculation, but in vessels of the arterial part of microcirculation no diffusion was found. That was to say that diffusion occurred in capillary and microvenous, but not in microarterial. It is expected that this method would be very useful for the quantitive analysis in various molecular weights and in monolayer endothelial cell permeability.

Relative functions of the alpha and beta subunits of the proteasome activator, PA28

PA28 is a 180,000-dalton protein that activates hydrolysis of small nonubiquitinated peptides by the 20 S proteasome. PA28 is composed of two homologous subunits, alpha and beta, arranged in alternating positions in a ring-shaped oligomer with a likely stoichiometry of (alphabeta)3. Our previous work demonstrated that the carboxyl terminus of the alpha subunit was necessary for PA28 to bind to and activate the proteasome. The goals of this work were to define the exact structural basis for this effect and to determine the relative roles of the alpha and beta subunits in proteasome activation. Each subunit and various mutants of the alpha subunit were expressed in Escherichia coli and purified. PA28alpha stimulated the proteasome, but had a much greater Kact than native heteromeric PA28. In contrast, PA28beta was unable to stimulate the proteasome. Mutants of the alpha subunit in which the carboxyl-terminal tyrosine residue was deleted or substituted with charged amino acids could neither bind to nor activate the proteasome. However, substitution of the carboxyl-terminal tyrosine with other amino acids resulted in proteins which could stimulate the proteasome to various extents. Tryptophan mutants stimulated the proteasome as well as did native PA28, whereas serine or phenylalanine mutants stimulated the proteasome much poorer than did wild type PA28alpha. Deletion of the "KEKE" motif, a 28-amino acid domain near the amino terminus of PA28alpha, had no effect on proteasome stimulatory activity. Hetero-oligomeric PA28 proteins were reconstituted from isolated wild type and mutant subunits. PA28 reconstituted from wild type subunits had structural and functional properties that were indistinguishable from those of the native hetero-oligomeric protein. PA28 molecules reconstituted from inactive alpha subunits and wild type beta subunits remained inactive. However, PA28 molecules reconstituted from suboptimally active alpha mutants and wild type beta subunits had the same activity as native heteromeric PA28. These results indicate that the beta subunit modulates PA28 activity, perhaps by influencing the affinity of PA28 for the proteasome.

[The prognostic values of FCM determination of primary tumor and axillary lymph node of the patients with breast cancer]

Using Flow cytometry, we determined the ploidy and SPF on the primary tumor and axillary lymph node of 58 patients with breast cancer. Follow up for 5 years evealed that 23 patients had recurrence. 21 of them died. We conclude that the patients with aneuploid and high SPF have a higher relapce rate than those with diploid and low SPF, especially in those with advanced stage tumor or metastatic lymph node. It seems that ploidy and SPF of primary tumors affect more strong the prognosis of the patient than those of axillary lymph node. The probable cause of the recurrence of diploid tumor patients suggest post operation treatment for the patients with aneuploid cancer.

Cytotoxic effects of MPTP on SH-SY5Y human neuroblastoma cells

Morphological and metabolic endpoints were used to evaluate MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) toxicity to SH-SY5Y human neuroblastoma cells. After 8 hours of exposure, MPTP was found to affect cell viability only at a very high concentration (3 x 10(-3) M), but its metabolite MPP+ could decrease viability at 10(-4) M. MPTP, via its metabolite MPP+, inhibited NADH dehydrogenase activity when concentrations exceeded 10(-4) M (for MPP+ 10(-5)M). The Ki were 2.4 x 10(-3) M and 3 x 10(-4)M for MPTP and MPP+, respectively. MPTP at concentrations greater than 10(-4) M altered cell morphology as early as one hour after exposure. These changes included formation of cell surface blebs and attenuated neurites. After 8 hours at 10(-3) M and 24 hrs at 10(-4) M, MPTP caused ultrastructural changes of mitochondria with increased electron-density of the matrix and disorganization of cristae, as well as abnormal aggregation of filamentous material of the cytoskeleton. Because these changes of structure and function took place at concentrations lower than those needed to affect cell viability, they may play a role in MPTP neurotoxicity in SH-SY5Y cell culture.

Tumor necrosis factor alpha plays a central role in immune-mediated clearance of adenoviral vectors

Adenovirus (Ad) gene transfer vectors are rapidly cleared from infected hepatocytes in mice. To determine which effector mechanisms are responsible for elimination of the Ad vectors, we infected mice that were genetically compromised in immune effector pathways [perforin, Fas, or tumor necrosis factor alpha (TNF-alpha)] with the Ad vector, Ad5-chloramphenicol acetyl transferase (CAT). Mice were sacrificed at 7-60 days postinfection, and the levels of CAT expression in the liver determined by a quantitative enzymatic assay. When the livers of infected mice were harvested 28 days postinfection, the levels of CAT expression revealed that the effectors most important for the elimination of the Ad vector were TNF-alpha > Fas > perforin. TNF-alpha did not have a curative effect on infected hepatocytes, as the administration of TNF-alpha to infected severe combined immunodeficient mice or to infected cultures in vitro had no specific effect on virus persistence. However, TNF-alpha-deficient mice demonstrated a striking reduction in the leukocytic infiltration early on in the infection, suggesting that TNF-alpha deficiency resulted in impaired recruitment of inflammatory cells to the site of inflammation. In addition, the TNF-deficient mice had a significantly reduced humoral immune response to virus infection. These results demonstrate a dominant role of TNF-alpha in elimination of Ad gene transfer vectors. This result is particularly important because viral proteins that disable TNF-alpha function have been removed from most Ad vectors, rendering them highly susceptible to TNF-alpha-mediated elimination.

[Preparation of liposomes of superoxide dismutase]

The liposomes of SOD were prepared by reverse-phase evaporation. By examining the important effects on preparation we obtained the liposomes of SOD. The encapsulation of SOD was more than 60%, and the stability of the liposomes was excellent.

[The relationship between the prognosis of retinoblastoma and proliferating cell nuclear antigen and argyrophilic protein at nucleolus organizer regions]

OBJECTIVE

To investigate the relationship between the proliferative activity of retinoblastoma (Rb) cells and the prognosis of the tumor.

METHODS

Proliferating cell nuclear antigen (PCNA) and argyrophilic nucleolar organizer regions (AgNORs) in paraffin-embedded Rb specimens from 48 cases were detected by LSAB immunohistochemical method using an anti-PCNA monoclonal antibody and the technique of ploton.

RESULTS

The PCNA labeling index (PCNALI) and the AgNORs counts were well correlated (r = 0.647, P < 0.001). In 29 patients of the 48 cases receiving simple eyeball extirpation and being followed up for 5 years, the mean PCNALI and the mean numbers of AgNORs per nucleus in 19 patients surviving > or = 5 years after operation were markedly lower than that in 10 patients surviving < 5 years after operation (P < 0.01, P < 0.05).

CONCLUSION

It is indicated that the PCNALI or the AgNOR count is negatively related with the clinical prognosis of Rb patients, and can be useful in judging the prognosis.

Cellular mechanisms for developmental toxicity of chlorpyrifos: targeting the adenylyl cyclase signaling cascade

Developmental neurotoxicity caused by chlorpyrifos exposure is generally thought to target cholinesterase but chlorpyrifos may also act on cellular intermediates, such as adenylyl cyclase, that serve global functions in the coordination of cell development. In the current study, neonatal rats were exposed to apparently subtoxic doses of chlorpyrifos (no weight loss, no mortality) either on Postnatal Days 1-4 or on Postnatal Days 11-14, and the effects on components of the adenylyl cyclase cascade were evaluated in brain regions that are enriched (forebrain) or sparse (cerebellum) in cholinergic innervation, as well as in a nonneural tissue (heart). In all three, chlorpyrifos evoked deficits in multiple components of the adenylyl cyclase cascade: expression and activity of adenylyl cyclase itself, functioning of G-proteins that link neurotransmitter and hormone receptors to cyclase activity, and expression of neurotransmitter receptors that act through this cascade. Disruption of signaling function was not restricted to transduction of cholinergic signals but rather extended to adrenergic signals as well. In most cases, the adverse effects were not evident during the immediate period of chlorpyrifos administration, but appeared after a delay of several days. These results suggest that chlorpyrifos can affect cell development by altering the activity and reactivity of the adenylyl cyclase signaling cascade, a major control point for trophic regulation of cell differentiation. The effects are not restricted to cholinergic targets, nor even to the central nervous system. Hence, disruption of cell development by chlorpyrifos is likely to be more widespread than previously thought.

[Vitrectomy for extraction of intraocular foreign bodies]

OBJECTIVE

To evaluate the effect of treatment of intraocular foreign bodies (IOFBs) with vitrectomy and its influential factors.

METHODS

A retrospective research was done on 517 in-patients having undergone extraction of IOFBs with vitrectomy.

RESULTS

Postoperatively, the successful rate of the extraction of IOFBs was 97.6%, the rate of cases with useful vision (0.05 to 0.4) increased from preoperative 12.5% to 23.2% and that with good vision (0.5 and better) from 7.2% to 17.0% (P < 0.005). When IOFBs were located in anterior segment, vitreous and retina, the increasing rates of cases with useful vision respectively were 44.4%, 25.1% and 10.7%, and that of good vision were 26.3%, 12.7% and 2.7%.

CONCLUSIONS

Vitrectomy is favorable for the extraction of IOFBs, the increase of postoperative vision and the management of complications.

Daily torpor and energy expenditure in Sminthopsis macroura: interactions between food and water availability and temperature

Endothermy allows maintenance of a constant internal thermal milieu for optimal physiological functions but results in high energy expenditure and water loss. Since torpor can reduce both expenditure of energy and loss of water and thus reduces food and water requirements, we determined how different food and water regimes affect torpor occurrence and patterns in the dasyurid marsupial Sminthopsis macroura at ambient temperatures of 18 degrees C (well below the thermoneutral zone) and 28 degrees C (close to the thermoneutral zone). At 18 degrees C, torpor was more frequent and more pronounced than at 28 degrees C. Withdrawal of food reduced the average daily metabolic rate by 20%; withdrawal of water alone had little effect. The average daily metabolic rate of individuals displaying torpor was 20% lower than that of individuals remaining normothermic. At 28 degrees C, the average daily metabolic rate under food restriction was 85% of that with food available ad lib. However, this reduction of average daily metabolic rate at 28 degrees C seems due not to the use of torpor but mainly to a reduction of the resting metabolic rate. The results suggest that at low temperature, torpor is used to adjust energy expenditure to availability of food, whereas at high temperature, reductions of resting metabolic rate are employed.

A GTPase-activating protein for the G protein Galphaz. Identification, purification, and mechanism of action

A GTPase-activating protein (GAP) specific for Galphaz was identified in brain, spleen, retina, platelet, C6 glioma cells, and several other tissues and cells. Gz GAP from bovine brain is a membrane protein that is refractory to solubilization with most detergents but was solubilized with warm Triton X-100 and purified up to 50,000-fold. Activity is associated with at least two separate proteins of Mr approximately 22,000 and 28,000, both of which have similar specific activities. In an assay that measures the rate of hydrolysis of GTP pre-bound to detergent-soluble Galphaz, the GAP accelerates hydrolysis over 200-fold, from 0.014 to 3 min -1 at 15 degrees C, or to >/=20 min-1 at 30 degrees C. It does not alter rates of nucleotide association or dissociation. When co-reconstituted into phospholipid vesicles with trimeric Gz and m2 muscarinic receptor, Gz GAP accelerates agonist-stimulated steady-state GTP hydrolysis as predicted by its effect on the hydrolytic reaction. In the single turnover assay, the Km of the GAP for Galphaz-GTP is 2 nM. Its activity is inhibited by Galphaz-guanosine 5'-O-thiotriphosphate (Galphaz-GTPgammaS) or by Galphaz-GDP/AlF4 with Ki approximately 1.5 nM for both species; Galphaz-GDP does not inhibit. G protein betagamma subunits inhibit Gz GAP activity, apparently by forming a GTP-Galphazbetagamma complex that is a poor GAP substrate. Gz GAP displays little GAP activity toward Galphai1 or Galphao, but its activity with Galphaz is competitively inhibited by both Galphai1 and Galphao at nanomolar concentrations when they are bound to GTPgammaS but not to GDP. Neither phospholipase C-beta1 (a Gq GAP) nor several adenylyl cyclase isoforms display Gz GAP activity.

Adsorption Enthalpy and Adsorption Isotherm of Tetradecylpyridinium Bromide on Na-Montmorillonite

The adsorption enthalpy and the adsorption isotherm of tetradecylpyridinium bromide (TPB) onto a Na-montmorillonite suspension and the dilution enthalpy of the TPB solution have been determined at 298.15 K. The dilution process is endothermic and the adsorption process is exothermic. For ion exchange adsorption, the interaction between TP+ and the montmorillonite is much stronger than that between Na+ and the montmorillonite because the cumulative adsorption enthalpy increases dramatically with adsorption amount. For molecular adsorption, however, the interaction between TPB and the clay is much weaker.

[The measurement of eye axial length by ultrasound]

Ultrasonic biometer is the best method of eye axial length measurement now. In this paper, our biometric method is introduced. It can measure the anterior chamber depth, lens thickness, vitreous length and axial length automatically, which are important to intraocular implant (IOL).

A model for the quaternary structure of the proteasome activator PA28

PA28 is a protein activator of the 20S proteasome. It has a native molecular weight of approximately 200,000 and is composed of six 28,000-dalton subunits arranged in a ring-shaped complex. Purified preparations of PA28 contain two polypeptides, alpha and beta, which are about 50% identical in primary structure. It has been unclear whether native PA28 consists of two distinct homohexameric proteins or of a single protein containing both alpha and beta subunits. To distinguish between these possibilities, we prepared antibodies that reacted specifically with either the alpha or beta subunit and used these subunit-specific antibodies in two types of experiments designed to elucidate PA28 quaternary structure. In the first experiment, the alpha and beta subunits were completely co-immunoprecipitated by each subunit-specific antibody, indicating that both subunits were part of a single protein complex. In the second experiment, PA28 was chemically cross-linked using bis(sulfosuccinimidyl)suberate. When the cross-linked products were immunoblotted after SDS-polyacrylamide gel electrophoresis, indistinguishable patterns were obtained with each subunit-specific antibody. These results confirm that the alpha and beta subunits were part of the same protein complex. The pattern of cross-linked products also provided insight as to the relative abundance and arrangement of the subunits within the PA28 complex and indicated that the ring-shaped PA28 hexamer may be composed of alternating alpha and beta subunits with a stoichiometry of (alphabeta)3. PA28 was inactivated by treatment with carboxypeptidase Y, which cleaved Tyr and Ile residues from the carboxyl terminus of the alpha subunit but had very little effect on the beta subunit. This selective and limited proteolysis prevented binding of both alpha and beta subunits to the proteasome and therefore provides additional evidence of the heterodimeric nature of PA28. These results indicate that a short carboxyl-terminal sequence of the alpha subunit is critical for binding of native PA28 to the proteasome. To learn about the relative functions of the alpha and beta subunits, PA28alpha was expressed in Escherichia coli and purified to homogeneity. Purified PA28alpha stimulated proteasome activity but required 5-10-fold greater concentrations than the heterodimeric PA28 to achieve a given level of activity. These results suggest that the heterodimeric structure of PA28 is required for maximal proteasome activation.

Signal transduction pathways in guinea pig sperm

Trifluoperazine (TFP), the antagonist of calmodulin (CaM), significantly stimulated the capacitation and acrosome reaction of guinea pig spermatozoa at the concentration of 10-100 mumol/L, independent of the external Ca2+. Forskolin, dbcAMP and caffeine evidently promoted the occurrence of acrosome reaction of spermatozoa at early capacitation stage (5 h) in nonsynchronous system but not in synchronous system. If the spermatozoa were capacitated for 15 h in synchronous system, the above three drugs significantly stimulated acrosome reaction in a Ca(2+)-independent manner. Protein kinase C activators, i.e. phorbol 12-myristate 13-acetate (PMA) and phorbol 12,13-dibutyrate (PDB) did not influence the occurrence of acrosome reaction of spermatozoa at early capacitation stage, but significantly increased the acrosome reaction rate in capacitated spermatozoa in a Ca(2+)-independent manner. In contrast, PKC inhibitor staurosporine significantly inhibited the occurrence of acrosome reaction.

Capillary electrophoresis-electrospray mass spectra of the herbicides paraquat and diquat

The positive ion electrospray mass spectra of the quaternary ammonium salt herbicides paraquat and diquat are examined by on-line separation with capillary electrophoresis (CE) and by direct infusion of the analytes. The analytes are separated by CE in 7-10 min at pH 3.9 in 50% methanol-water by using several different separation buffer electrolytes. The capillary electrophoresis-electrospray ionization (CE-ES) mass spectra of paraquat and diquat consist primarily of doubly charged molecular ions, singly charged molecular ions, and singly charged deprotonated ions. The direct infusion spectra consist primarily of doubly charged molecular ions and singly charged deprotonated ions. The relative abundances of the doubly charged and deprotonated ions depend strongly on the presence or absence of ammonium ion in the CE separation buffer or the direct infusion solution. A deprotonation mechanism is proposed in which the free base ammonia is the deprotonating agent in the desolvating charged droplets or in the gas phase. The analytical potential of the CE-ES electrospray approach for environmental analyses is evaluated in terms of the precision of replicate injections, linear concentration range, and estimated detection limit.

Oligonucleotide uptake in human hematopoietic cells is increased in leukemia and is related to cellular activation

The use of antisense oligonucleotides as tools for modulating gene expression represents a novel strategy for designing drugs to treat a variety of diseases. Several factors, including cellular uptake and internalization of the oligonucleotides, are important parameters in determining the effectiveness of antisense agents such as therapeutic drugs. We have studied oligonucleotides uptake in normal and leukemic human hematopoietic cells, such as peripheral blood, bone marrow (BM), and HL-60 cell line; and have found that, in normal human blood and BM, myeloid cells and B cells preferably took up more oligonucleotides than T cells. There was no marked difference in oligonucleotide uptake between CD4+ helper T cells and CD8+ cytolytic T cells. Leukemic cells had greater oligonucleotide uptake than their normal counterparts. Furthermore, oligonucleotide uptake was closely related to cell activation status and can be modulated by growth factors or inhibitors. These studies provide a basis for using oligonucleotides as therapeutic drugs both in vitro and in vivo.

Secreted amyloid beta-protein similar to that in the senile plaques of Alzheimer's disease is increased in vivo by the presenilin 1 and 2 and APP mutations linked to familial Alzheimer's disease

To determine whether the presenilin 1 (PS1), presenilin 2 (PS2) and amyloid beta-protein precursor (APP) mutations linked to familial Alzheimer's disease (FAD) increase the extracellular concentration of amyloid beta-protein (A beta) ending at A beta 42(43) in vivo, we performed a blinded comparison of plasma A beta levels in carriers of these mutations and controls. A beta 1-42(43) was elevated in plasma from subjects with FAD-linked PS1 (P < 0.0001), PS2N1411 (P = 0.009), APPK670N,M671L (P < 0.0001), and APPV7171 (one subject) mutations. A beta ending at A beta 42(43) was also significantly elevated in fibroblast media from subjects with PS1 (P < 0.0001) or PS2 (P = 0.03) mutations. These findings indicate that the FAD-linked mutations may all cause Alzhelmer's disease by increasing the extracellular concentration of A beta 42(43), thereby fostering cerebral deposition of this highly amyloidogenic peptide.

[Pterygium and lipid peroxidation]

OBJECTIVE

The mechanism of light damage causing pterygium was investigated from the point of view of lipid peroxidation.

METHODS

22 patients with pterygium underwent excision of pterygium and a little superior bulbar conjunctiva was excised as normal control. The lipid peroxidation reaction of both pathologic and normal samples was analyzed by measuring the concentration of malondialdehyde.

RESULT

The concentration of malondialdehyde in the pathologic samples was much higher than that in the normal samples (P < 0.01).

CONCLUSION

Light Induced peroxidation reaction is closely related to the pterygium formation.