[An experimental study on epikeratophakia]

OBJECTIVE

The study was designed to investigate the corneal changes at various times after epikeratophakia performed on rabbit cornea.

METHODS

The process of epithelial repair, or interlayer healing, the changes of endothelial cells and Langerhans cells (LC) in corneal epithelium were observed at different intervals after surgery by using histochemistry technique.

RESULTS

The epithelial repair of the graft was completed by 4-12 postoperative days. The repopulation of keratocytes was seen firstly at peripheral and superior part of the lenticule at 7-14 postoperative days and completed to normal by postoperative 2 months. No changes were observed in the endothelial cells. The proliferation of LC was observed in the limbal epithelium at day 3, reached the peak by day 14 and recovered to normal at month 2 postoperatively.

CONCLUSION

Epikeratophakia is available and safe, The proliferation of LC might result from wound healing not from immune rejection.

Biological activities of human tumor necrosis factor-alpha and its novel mutants

Biological activities of human tumor necrosis factor-alpha (hTNF-alpha) and its mutants were compared. In cytotoxicity assay with L929 cells, one mutant, designated as TNF-B, showed 4.5-fold higher activity than TNF examined. In receptor binding assay, TNF-B had almost the same affinity for TNF receptors on L929 cells as hTNF-alpha. We also found that TNF-B retained the cytotoxicity of hTNF-alpha for HEp-2 cells. TNF-B also had two-fold higher affinity than hTNF-alpha for receptors on HEp-2 cells (only carrying hTNF-R55) and lower affinity for receptors on U937 cells (expressing mainly hTNF-R75). These results suggested that TNF-B might still interact with the human TNF-R55 receptor, but it might largely lose its ability to bind to human TNF-R75. Changes of biological activity of TNFs might be due to an altered affinity to the different types of TNF receptor on the target cells.

Biological activities of human tumor necrosis factor-alpha and its novel mutants

Biological activities of human tumor necrosis factor-alpha (hTNF-alpha) and its mutants were compared. In cytotoxicity assay with L929 cells, one mutant, designated as TNF-B, showed 4.5-fold higher activity than TNF examined. And TNF-B also increased cytostatic activity and decreased protein synthesis against U937 cells. In receptor binding assay, TNF-B had almost the same affinity for TNF receports on L929 cells as hTNF-alpha. But another mutant, TNFarg, markedly decreased the all activities of hTNF-alpha and had lower affinity for receports on different types of target cell. These results indicated that the relative activity of TNFs to target cells may correlate with their affinity for receports. We also found that TNF-B retained the cytotoxicity of hTNF-alpha for HEp-2 cells. TNF-B also had two-fold higher affinity than hTNF-alpha for receptors on HEp-2 cells (only carrying hTNF-R55) and lower affinity for receptors on U937 cells (expressing mainly hTNF-R75). These results suggested that TNF-B might still interact with the human TNF-R55 receptor, but it might largely lose its ability to bind to human TNF-R75. Changes of biological activity of TNFs might be due to an altered affinity to the different types of TNF receptor on the target cells.

Cataract extraction and intraocular lens implantation with anterior vitrectomy in children

OBJECTIVE

Extracapsular cataract extraction (ECCE) with selective intraocular lens (IOL) implantation has been the choice of the treatment for children with cataracts. With regard to surgical technique, ECCE with anterior segment vitrectomy has shown some success in reducing complications. Formation of a secondary membrane and opacity of the posterior capsule, however, are still major postoperative complications. To reduce these complications, we modified current surgical procedures with minimal incisions and manipulations.

PATIENTS AND METHODS

ECCE with anterior segment vitrectomy was performed using Storz Protage's system in 84 eyes of 58 children ranging in age from 14 months to 14 years. Of 70 eyes of children aged above 3 years, IOLs were implanted simultaneously. Vision improvement and incidence of postoperative complications were compared with other standard procedures to determine the benefits of the operation for children with cataracts. After the anterior capsule was opened by continuous circular capsulorhexis or envelope-form capsulectomy, the lens cortex was excised. Subsequently, the IOL was implanted into the bag.

RESULTS

Nine-30 months follow-up showed that all of the central area of the posterior capsule remained clear except one eye in which a secondary membrane was partially formed on the anterior surface of vitreous. No other operative or postoperative complications occurred.

CONCLUSIONS

The results indicate that the modified procedure is beneficial in the prevention of secondary cataract formation and other postoperative complications in a short term follow-up, however, a long-term follow-up is warranted to evaluate its role in pediatric cataract surgery.

[Penetrating keratoplasty in children]

OBJECTIVE

The study was designed to approach the operative techniques of penetrating keratoplasty (PKP) in children and the influential factors on the rate of graft clarity.

METHODS

PKP was performed on 33 eyes of 30 children whose corneal opacities resulted from various causes and they were followed for 6 months to 3 years.

RESULTS

The rate of graft clarity was 66.7% and 44.8% of these eyes were relieved from blindness. The poorest results achieved were in cases with congenital corneal opacity and the main cause of graft failure is endothelial immune rejection.

CONCLUSION

Although the surgical results in children are poorer than that in adults, from the concern of prevention of amblyopia and cosmetic problem, it is necessary to perform the operation earlier.

[Isolation and reassociation of acetogen and methanogen in a syntrophobic coculture degrading butyrate anaerobically]

Anaerobic coculture BF2 which degraded butyrate into acetate and produced methane was isolated from granular methanogenic sludge. The coculture is associated syntrophically the Syntrophomonas subsp. saponavida strain CF2 with Methanobacterium formicicum strain MF2 and appeared to degraded C4 approximately C18 fatty acids including isobutyrate. The optimal temperature and pH for growth was 37 degrees C and 7.7 respectively. The strain CF2 was obtained in pure culture with crotonate as substrate and produces acetate and butyrate. The doubling time of strain CF2 in crotonate media was about 20 hours. Strain CF2 is Gram negative, slightly curved 0.2 approximately 0.3 x 2.0 approximately 3.0 micron with round ends, motile by lateral flagellation at the concave side, non sporeforming. With a hydrogen scavenging organism, such as Methanospillum hungatei JF1, Methanobacterium formicicum 1535, Methanobrevibacterium bryantii 1125 and Desulfovibrio sp. B11, the strain CF2 paired up and the defined coculture degraded butyrate to acetate. When the strain CF2 associated with the original accompanist, Methanobacterium formicius strain MF2, the reassociated couculture degraded butyrate to acetate and produced methane again.

Carbohydrate-binding proteins (plant/human lectins and autoantibodies from human serum) as mediators of release of lysozyme, elastase, and myeloperoxidase from human neutrophils

Analysis of cell surface glycosylation not only provides information about cell properties such as their state of differentiation or histogenetic lineage. The carbohydrate chains also provide potentially functional binding sites to endogenous carbohydrate-binding proteins. This interaction can elicit consequent signalling processes. Because of the importance of neutrophils in the host defence system, we monitored the effect of the binding of such sugar receptors to their cell surface on the release of the enzymatic activities of lysozyme, elastase, and myeloperoxidase. Besides the mannose-binding lectin concanavalin A and the immunomodulatory alpha/beta-galactoside-binding lectin from Viscum album L., three preparations of human sugar receptors - beta-galactoside-binding lectin (M(r) 14 kDa) and two affinity-purified polyclonal IgG fractions from serum with the capacity to recognize alpha- or beta-galactosides, respectively - were used. Two animal lectins from chicken liver and intestine that bind beta-galactosides, as well as the lectin-like human serum amyloid P component, were included in order to assess the importance of slight differences in ligand recognition. Cytochalasin B-enhanced enzyme release was invariably seen with the two plant lectins and the chicken liver beta-galactoside-binding lectin, but the related intestinal lectin did not increase enzyme release. The mammalian homologue of these avian lectins triggered lysozyme secretion, and the lactoside-binding IgG fraction enhanced the amount of extracellular elastase activity slightly but significantly. Thus, the actual lectin, not the nominal specificity of sugar receptors, is crucial for elucidation of responses. Due to the highly stimulatory activity of the two plant lectins, neutrophils from patients with non-cancerous diseases and from patients with lung cancer were monitored for the extent of lectin-mediated enzyme release. Only the concanavalin A-mediated reactivity of the neutrophils was associated with the type of disease.

[A preliminary report on extracapsular cataract extraction with intraocular lens implantation in children]

Extracapsular cataract extraction (ECCE) with posterior chamber intraocular lens (IOL) implantation was performed on 94 eyes of children who were followed up for 6 approximately 30 months. IOLs were inserted in all of these eyes successfully with anterior vitrectomy used in several cases with traumatic cataract. The postoperative managements were similar to those in adults, but their complications were severer obviously than those of adults. Uveitis was the main postoperative complication which was characterized by severer anterior chamber reaction, longer duration and easier to form posterior iris synechiae and develop posterior capsular opacity. The follow-up results showed that the unilateral recovery rate from blindness is 90.1%, and 49.4% of these patients' corrected visual acuities were below 0.4. Because of the controversy on IOL implantation in children, it is the authors opinion that it should be cautious to perform IOL implantation on children and such an operation is not advocated for children under 3 years old. Children with unilateral cataract should be managed by experienced doctors, and it is very important to follow up carefully, to correct refractive error and carry out amblyopia treatment.

Role of formate and hydrogen in the degradation of propionate and butyrate by defined suspended cocultures of acetogenic and methanogenic bacteria

The butyrate-degrading Syntrophospora bryantii degrades butyrate and a propionate-degrading strain (MPOB) degrades propionate in coculture with the hydrogen- and formate-utilizing Methanospirillum hungatii or Methanobacterium formicicum. However, the substrates are not degraded in constructed cocultures with two Methanobrevibacter arboriphilus strains which are only able to consume hydrogen. Pure cultures of the acetogenic bacteria form both hydrogen and formate during butyrate oxidation with pentenoate as electron acceptor and during propionate oxidation with fumarate as electron acceptor. Using the highest hydrogen and formate levels which can be reached by the acetogens and the lowest hydrogen and formate levels which can be maintained by the methanogens it appeared that the calculated formate diffusion rates are about 100 times higher than the calculated hydrogen diffusion rates.

Age-related development of human anti-pig xenoantibody

Human cytotoxic natural xenoantibodies are believed to be of the immunoglobulin M class in nature. However, a thorough understanding of the development of these natural antixenodonor xenoantibodies remains incomplete. In this study, serum samples were obtained from newborn, infant, and adult human beings. An enzyme-linked immunosorbent assay was used to determine the binding of human natural immunoglobulin M xenoantibodies to pig aortic endothelial cells and pig lymphocytes. A complement-mediated cytotoxicity assay was used to measure the cytotoxicity of newborn, infant, and adult serum to cultured pig aortic endothelial cells and pig lymphocytes. Adult human serum contained both natural immunoglobulin M and immunoglobulin G xenoantibodies to pig endothelial cells and lymphocytes, whereas newborn infant serum contained only immunoglobulin G xenoantibodies. Only adult human serum was cytotoxic to pig endothelial cells and lymphocytes. Human immunoglobulin M xenoantibodies became detectable by age 1 month. By age 2 months these natural anti-pig xenoantibodies reached serum levels equivalent to those in the human adult and resulted in similar cytotoxicity to that of adult human serum. These findings indicate that (1) natural anti-pig immunoglobulin M xenoantibodies are absent from newborn infant human serum, (2) newborn human serum is not cytotoxic to pig endothelial cells and lymphocytes despite the presence of immunoglobulin G xenoantibodies that bind to pig endothelial cells and lymphocytes, and (3) natural anti-pig immunoglobulin M xenoantibodies begin to develop as early as age 1 month and by age 2 months attain a circulating level comparable to that found in the adult.

[An experimental study on HSV-1 corneal latency by in situ nucleic acid hybridization]

An experimental study was performed on animal models for evaluation of the possibility of herpes simplex virus-1 (HSV-1) corneal latency by in situ nucleic acid hybridization. 20 normal New Zealand white (NZW) rabbits were used, and 3 x 10(6) PFU/ml of McKrae strain HSV-1 was inoculated bilaterally into the corneal stroma in 14 rabbit eyes. Of the 28 eyes, 22 developed typical herpes simplex keratitis (HSK). On the postoperative 60th day, 4 corneas with latent infection were transplanted into one unilateral eyes of each 4 non-infected NZW rabbits respectively and removed 2 weeks postoperatively. The corneal buttons were individually detected for the presence of HSV-1 antigen and nucleic acid sequences by using clonal IgG HSV-1 antibody and biotinylated HSV-1 DNA probe respectively. The results showed that the HSV-1 DNA sequences retained only within the corneal stromal layer with negative HSV-1 antigen staining. These results strongly suggest that the cornea be capable of harboring latent HSV-1.

Affinity-purified antibodies against alpha-galactosyl residues from human serum: comparison of their binding in bovine testicular tissue with that of the Griffonia simplicifolia lectin (GSI-B4) and impact of labeling on epitope localization

alpha-Galactosyl residues in the carbohydrate part of cellular glycoconjugates can serve as cell type-associated markers and are implicated in intercellular adhesion and biosignaling. This biological significance explains the interest to characterize probes with respective specificity as the Griffonia simplicifolia I-isolectin B4. Due to the documented occurrence of an alpha-galactoside-binding immunoglobulin G fraction in human serum we compared the extent of binding and its pattern for the lectin and the antibody using surface-immobilized extract proteins and fixed sections of bovine testicular tissue with known lectin reactivity. The antibody fractions were obtained either solely from affinity chromatography isolation on immobilized melibiose or after an additional step to deplete this fraction of galactoside-binding activities without pronounced specificity to the alpha-anomeric linkage. They yielded a rather indistinguishable reactivity in comparison to that of the lectin, when an indirect approach was used. Labeling of the antibodies with a hydrazide derivative of biotin did not affect the pattern of binding. However, significant differences were noted, when conjugation of label was targeted to amino groups via N-hydroxy-succinimide esters of biotin and digoxigenin despite performance of the modification under activity-preserving conditions. Notably, the apparent strong staining of Leydig cells and nuclei of primary spermatocytes, respectively, was not inhibitable by sugar. These differences were corroborated by a nonidentical response of the various probes in solid-phase assays with extract proteins. Thus, care should be exercised in the interpretation of histochemical data, obtained with this type of modified antibody. When these precautions are fulfilled, this immunoglobulin fraction from human serum has the potential as an alpha-galactosyl-specific histochemical tool.

A study on HSV-1 corneal potential infection by in situ nucleic acid hybridization

PURPOSE

To evaluate the possibility of HSV-1 corneal latency by in situ nucleic acid hybridization in animal models.

METHODS

20 normal New Zealand White (NEW) rabbits were used, 14 of them were inoculated bilaterally with 3 x 10 PFU/ml of McKrae strain HSV-1 by intrastromal injection. 22/28 eyes developed typical herpes simplex keratitis (HSK) diseases. At 60 day postoperation (PI), 4 latent corneas were transplanted to one eye of 4 noninfected NZW rabbits and removed 2 weeks PI. Corneas at all time intervals of infection and two weeks after PKP were detected for presence of HSV-1 antigen and nucleic acid sequences by using clonal IgG HSV-1 antibody and biotinylated HSV-1 DNA probe individually.

RESULTS

The results showed that the HSV-1 DNA sequences were retained within the corneal epithelium and anterior stromal keratocytes during acute diseases, while the corneas during latent infection and postoperation, the HSV-1 DNA sequences were retained only within the stromal layer with negative HSV-1 antigen staining.

CONCLUSIONS

These results strongly suggest that the cornea may be capable of harboring latent HSV-1.

Natural antipig xenoantibody is absent in neonatal human serum

BACKGROUND

Discordant xenotransplantation represents an attractive alternative to allotransplantation in light of the current shortage of donor organs suitable for heart allotransplantation. Unfortunately, discordant xenotransplantation is still limited by hyperacute rejection, a process thought to be mediated by natural antixenodonor antibodies. On the basis of our previous findings that cytotoxic natural xenoantibodies are immunoglobulin M in nature and that natural immunoglobulin M xenoantibodies are barely detectable in neonatal baboon serum, we postulated that immunoglobulin M xenoantibodies may be absent from newborn human serum.

METHODS

Neonatal human sera were obtained from the cord blood of normal term infants and pooled. Pooled adult human sera were used as a control. A whole cell enzyme-linked immunosorbent assay and a complement-mediated cytotoxicity assay were performed to determine the binding and cytotoxicity of these xenoantibodies to pig aortic endothelial cells and pig lymphocytes.

RESULTS

Neonatal human sera did not show binding of immunoglobulin M xenoantibodies to pig aortic endothelial cells or lymphocytes. However, low level binding of immunoglobulin G xenoantibodies was detected to pig endothelial cells and lymphocytes. In contrast, adult human sera showed significant binding of both natural immunoglobulin M and G xenoantibodies to pig aortic endothelial cells and lymphocytes. In addition, adult human immunoglobulin M xenoantibodies bound with similar avidity to both cultured adult and neonatal pig aortic endothelial cells. Although neonatal human sera were not cytotoxic to target cells, adult sera were cytotoxic to both pig aortic endothelial cells and pig lymphocytes. Our findings indicate that neonatal human sera lack natural antipig immunoglobulin M xenoantibodies, and therefore, neonatal human serum is not cytotoxic to pig endothelial cells or lymphocytes. Like adult pig endothelial cells, neonatal pig endothelial cells may also express similar membrane xenoantigens recognized by natural immunoglobulin M xenoantibodies.

CONCLUSIONS

The absence of cytotoxic natural immunoglobulin M xenoantibodies in the neonate suggests that discordant xenotransplantation may be feasible in the neonate.

Time of symptom onset of eight common medical emergencies

Specific time periods of the day may be associated with different frequencies of symptom onset in different diseases. The purpose of the current study was to examine times of symptom onset in eight commonly encountered emergent conditions--cerebral infarction, cerebral hemorrhage, transient ischemic attacks, cardiac dysrhythmias, angina pectoris, acute myocardial infarction, gastrointestinal bleeding, and acute asthma. Data from 4554 cases were retrospectively reviewed. Symptom onset frequency curve diagrams were derived, illustrating peak hours of symptom presentation for each of the eight emergent conditions. Hormonal and metabolic factors that may be related to diurnal variations in symptom onset of the eight diseases are briefly discussed.

[A clinical observation on intraocular lens implantation in high myopic eyes with cataract]

Extracapsular cataract extraction (ECCE) with intraocular lens (IOL) implantation was performed on 124 high myopic eyes with cataract of 101 cases whose mean period of follow-up was 16.4 months. Post-operatively, 95.97% of these eyes were relieved from blindness and 75.00%, from visual handicap. The incidence of posterior capsular opacity was 22.58% and only did 1.61% of the eyes occur retinal detachment. Intraoperatively, posterior capsular rupture occurred in 5.65% of the eyes. The results indicate that ECCE with IOL implantation performed on eyes with high myopia and cataract is effective.

[Effects of Sichuan herba Epimedii on the concentration of plasma middle molecular substances and sulfhydryl group of "yang-deficiency" model animal]

The effects of tonifying the kidney and strengthening the "Yang" produced by the extracts of Chinese herbs Epimedium wushanense and E. pubescens were studied in this paper. The results showed that both two herbs could decrease the concentration of plasma middle molecular substances and increase the concentration of plasma sulfhydryl group of "Yang-deficiency" model mice, thus suggesting that the above-said tonifying and strengthening effects of Herba Epimedii may result from its effects on middle molecular substances and sulfhydryl group, so as to strengthen the body resistance and eliminate the invading pathogenic factors.

Creation of a high cytotoxic active human tumor necrosis factor having the truncated and more basic amino terminus

In order to define the structure-functional relationship of tumor necrosis factor(TNF), a mutant TNF gene was created by site-specific mutagenesis based on the PCR technique. This gene was highly expressed in E.coli cells. The amount of the recombinant protein was up to about 80% of the total cellular proteins. Through one-step ion exchange chromatography, the mutant TNF could be purified to homogeneity. This mutein showed the molecular weight of a dimer but not a trimer. It bears the features of truncated amino terminus and increase of the basicity of amino terminal residues. Compared with the wild type TNF, the specific activity of mutant TNF was increased by fourfold.

Localization of the enzymes involved in H2 and formate metabolism in Syntrophospora bryantii

Cell-free extracts of crotonate-grown cells of the syntrophic butyrate-oxidizing bacterium Syntrophospora bryantii contained high hydrogenase activities (8.5-75.8 mumol.min-1mg-1 protein) and relatively low formate dehydrogenase activities (0.04-0.07 mumol.min-1 mg-1 protein). The KM value and threshold value of the hydrogenase for H2 were 0.21 mM and 18 microM, respectively, whereas the KM value and threshold value of the formate dehydrogenase for formate were 0.22 mM and 10 microM, respectively. Hydrogenase, butyryl-CoA dehydrogenase and 3-OH-butyryl-CoA dehydrogenase were detected in the cytoplasmic fraction. Formate dehydrogenase and CO2 reductase were membrane-bound, likely located at the outer aspect of the cytoplasmic membrane. Results suggest that during syntrophic butyrate oxidation H2 is formed intracellularly while formate is formed at the outside of the cell.

Are matrix-immobilized neoglycoproteins, plant and human lectins and carbohydrate--binding antibodies from human serum mediators of adhesion in vitro for carcinoma and lymphosarcoma cells?

Mediation of cell adhesion by defined molecules can be studied by their immobilization onto a nitrocellulose matrix and incubation with cells. In order to infer the capacity of deliberately selected protein-carbohydrate interactions to establish sugar-inhibitable cell adhesion, a panel of immobilized neoglycoproteins was employed for the murine lymphosarcoma lines RAW-117 with low (P) and high (H10) metastatic capacity, a human mammary carcinoma line (DU4475) and three human colon carcinoma lines (C205, SW480, SW620). Exhibiting an otherwise rather similar behavior relative to the line with low metastatic potential, the murine line RAW117-H10 bound strongly to the matrix with carboxyl group-bearing N-acetylneuraminic acid and glucuronic acid as well as rhamnose. Whereas the analysis of carbohydrate-mediated adhesion yielded comparable results for the three colon carcinoma lines, a markedly reduced number of adherent cells was counted for matrix-attached alpha- and beta-galactosyl, alpha-mannosyl and alpha-glucosyl moieties in the case of the mammary carcinoma line, raising evidence for cell lineage-dependent alterations of this property. From the carbohydrate-binding proteins, the plant lectin, concanavalin A and Viscum album agglutinin almost invariably served well as cell adhesion molecules. Appropriate cell surface sugar receptors, probed with neoglycoproteins, and glycoconjugates, probed with lectins, thus can contribute to adhesion in this model system. The immobilized human beta-galactoside-binding lectin (Mr 14kDa) caused adhesion of the murine lines and one colon carcinoma line (SW480). Neither C-reactive protein under conditions that induce its activity as lectin nor serum amyloid P component nor a lactose-binding immunoglobulin G fraction from human serum were reactive. However, cell adhesion to the alpha-galactoside-binding immunoglobulin G fraction of human serum was seen with the murine line of low metastatic capacity and the mammary carcinoma line. Cells of this line adhered also to the mannan-binding protein from human serum, supporting the view for its potential role in host defence against aberrantly glycosylated tumor cells.

[An investigation on therapeutic results of extracapsular cataract extraction and intraocular lens implantation in diabetics]

44 cases (50 eyes) with diabetes and cataract were followed up for 6-30 months after extracapsular cataract extraction (ECCE) with intraocular lens implantation (IOL). No severe intra- and post-operative complications were found and 84% of eyes obtained post-operative corrected visual acuities > or = 0.5. The results suggest that the pre-operative hyperglycemia alone be not a contraindication of the operation. Pre-operatively, if the diabetes of patients with cataract can be controlled by diet or hypoglycemic agent, their glucose level in the blood remains normal and stable for a period of time and there are no other systemic and ocular complications, ECCE with IOL can be performed on such patients and the therapeutic results of the operation can be safe and reliable.

Abrogation of baboon natural xenoantibody to pig splenocytes by DL-penicillamine

Natural xenoantibodies are believed to be IgM in nature and are known to play a critical role in the hyperacute rejection of distantly related xenografts. The purpose of this study was to determine whether the reducing agent DL-penicillamine could inactivate baboon natural xenoantibodies to pig splenocytes. Pooled baboon serum was treated with varying concentrations of DL-penicillamine over different lengths of time and a complement-mediated cytotoxicity assay was used to determine the reactivity of baboon natural xenoantibodies to pig splenocytes. A whole-cell ELISA assay was used to assess the binding of both IgG and IgM xenoantibodies to pig splenocytes. In addition, DL-penicillamine-treated serum was dialyzed to assess its potential clinical application. These in vitro experiments indicate that both IgM and IgG baboon natural xenoantibodies bind to pig splenocytes, but only IgM xenoantibody is cytotoxic. The binding of baboon natural IgM xenoantibody can be eliminated, and the cytotoxicity of IgM xenoantibody markedly reduced by DL-penicillamine treatment despite continued binding of IgG xenoantibody to pig splenocytes. In addition, DL-penicillamine can be dialyzed, suggesting that it may be an efficacious clinical treatment, the toxicity of which can be regulated with hemodialysis.

A mutation in Arabidopsis that leads to constitutive expression of systemic acquired resistance

Systemic acquired resistance (SAR) is a nonspecific defense response in plants that is associated with an increase in the endogenous level of salicylic acid (SA) and elevated expression of pathogenesis-related (PR) genes. To identify mutants involved in the regulation of PR genes and the onset of SAR, we transformed Arabidopsis with a reporter gene containing the promoter of a beta-1,3-glucanase-encoding PR gene (BGL2) and the coding region of beta-glucuronidase (GUS). The resulting transgenic line (BGL2-GUS) was mutagenized, and the M2 progeny were scored for constitutive GUS activity. We report the characterization of one mutant, cpr1 (constitutive expressor of PR genes), that was identified in this screen and shown by RNA gel blot analysis also to have elevated expression of the endogenous PR genes BGL2, PR-1, and PR-5. Genetic analyses indicated that the phenotype conferred by cpr1 is caused by a single, recessive nuclear mutation and is suppressed in plants producing a bacterial salicylate hydroxylase, which inactivates SA. Furthermore, biochemical analysis showed that the endogenous level of SA is elevated in the mutant. Finally, the cpr1 plants were found to be resistant to the fungal pathogen Peronospora parasitica NOCO2 and the bacterial pathogen Pseudomonas syringae pv maculicola ES4326, which are virulent in wild-type BGL2-GUS plants. Because the cpr1 mutation is recessive and associated with an elevated endogenous level of SA, we propose that the CPR1 gene product acts upstream of SA as a negative regulator of SAR.

A mutation in Arabidopsis that leads to constitutive expression of systemic acquired resistance

Systemic acquired resistance (SAR) is a nonspecific defense response in plants that is associated with an increase in the endogenous level of salicylic acid (SA) and elevated expression of pathogenesis-related (PR) genes. To identify mutants involved in the regulation of PR genes and the onset of SAR, we transformed Arabidopsis with a reporter gene containing the promoter of a beta-1,3-glucanase-encoding PR gene (BGL2) and the coding region of beta-glucuronidase (GUS). The resulting transgenic line (BGL2-GUS) was mutagenized, and the M2 progeny were scored for constitutive GUS activity. We report the characterization of one mutant, cpr1 (constitutive expressor of PR genes), that was identified in this screen and shown by RNA gel blot analysis also to have elevated expression of the endogenous PR genes BGL2, PR-1, and PR-5. Genetic analyses indicated that the phenotype conferred by cpr1 is caused by a single, recessive nuclear mutation and is suppressed in plants producing a bacterial salicylate hydroxylase, which inactivates SA. Furthermore, biochemical analysis showed that the endogenous level of SA is elevated in the mutant. Finally, the cpr1 plants were found to be resistant to the fungal pathogen Peronospora parasitica NOCO2 and the bacterial pathogen Pseudomonas syringae pv maculicola ES4326, which are virulent in wild-type BGL2-GUS plants. Because the cpr1 mutation is recessive and associated with an elevated endogenous level of SA, we propose that the CPR1 gene product acts upstream of SA as a negative regulator of SAR.

Characterization of an Arabidopsis Mutant That Is Nonresponsive to Inducers of Systemic Acquired Resistance

Systemic acquired resistance (SAR) is a general defense response in plants that is characterized by the expression of pathogenesis-related (PR) genes. SAR can be induced after a hypersensitive response to an avirulent pathogen or by treatment with either salicylic acid (SA) or 2,6-dichloroisonicotinic acid (INA). To dissect the signal transduction pathway of SAR, we isolated an Arabidopsis mutant that lacks the expression of an SA-, INA-, and pathogen-responsive chimeric reporter gene composed of the 5[prime] untranslated region of an Arabidopsis PR gene, [beta]-1,3-glucanase (BGL2), and the coding region of [beta]-glucuronidase (GUS). This mutant, npr1 (nonexpresser of PR genes), carries a single recessive mutation that abolishes the SAR-responsive expression of other PR genes as well. While SA-, INA-, or avirulent pathogen-induced SAR protects wild-type plants from Pseudomonas syringae infection, the mutant cannot be protected by pretreatment with these inducers. The insensitivity of npr1 to SA, INA, and avirulent pathogens in SAR induction indicates that these inducers share a common signal transduction pathway. Moreover, in npr1, the localized expression of PR genes induced by a virulent Pseudomonas pathogen is disrupted, and the lesion formed is less confined. These results suggest a role for PR genes in preventing the proximal spread of pathogens in addition to their suggested role in SAR.

Characterization of an Arabidopsis Mutant That Is Nonresponsive to Inducers of Systemic Acquired Resistance

Systemic acquired resistance (SAR) is a general defense response in plants that is characterized by the expression of pathogenesis-related (PR) genes. SAR can be induced after a hypersensitive response to an avirulent pathogen or by treatment with either salicylic acid (SA) or 2,6-dichloroisonicotinic acid (INA). To dissect the signal transduction pathway of SAR, we isolated an Arabidopsis mutant that lacks the expression of an SA-, INA-, and pathogen-responsive chimeric reporter gene composed of the 5[prime] untranslated region of an Arabidopsis PR gene, [beta]-1,3-glucanase (BGL2), and the coding region of [beta]-glucuronidase (GUS). This mutant, npr1 (nonexpresser of PR genes), carries a single recessive mutation that abolishes the SAR-responsive expression of other PR genes as well. While SA-, INA-, or avirulent pathogen-induced SAR protects wild-type plants from Pseudomonas syringae infection, the mutant cannot be protected by pretreatment with these inducers. The insensitivity of npr1 to SA, INA, and avirulent pathogens in SAR induction indicates that these inducers share a common signal transduction pathway. Moreover, in npr1, the localized expression of PR genes induced by a virulent Pseudomonas pathogen is disrupted, and the lesion formed is less confined. These results suggest a role for PR genes in preventing the proximal spread of pathogens in addition to their suggested role in SAR.

Expression of intestinal fatty acid binding protein in intestinal epithelial cell lines, hBRIE 380 cells

Intestinal fatty acid binding protein (I-FABP) is a cytosolic protein present only in differentiated intestinal epithelial cells. Here we report on an intestinal cell culture system expressing I-FABP during cell differentiation and the modulation of expression by extracellular factors. An I-FABP-expressing cell line (hBRIE 380i) was generated from Berkeley rat intestinal epithelial cells (hBRIE 380). Time- and substratum-dependent changes in I-FABP mRNA expression were paralleled by changes in protein levels. Induction of I-FABP levels observed on collagen type I gels in the presence of limiting serum was prevented by insulin. When cells were grown on collagen gels containing fibronectin and laminin, a stimulation of ultrastructural characteristics of cell differentiation was observed with no further induction of I-FABP expression. The data show that I-FABP expression is limited to a differentiated population of hBRIE 380i cells and that the expression can be regulated by factors present in the extracellular matrix as well as involved in regulation of replication or metabolic state of the cell.

[An experimental study on cultivation of human trigeminal ganglionic cell in vitro and its sensitivity to infection of herpes simplex virus type 1]

We firstly report an experimental study on the sensitivity of primary cultural human trigeminal ganglionic cells infected by herpes simplex virus type 1 (HSV-1) in different time-points. The results indicate that the neuron of human trigeminal ganglia is the most sensitive cell type, the antigen of HSV-1 replicates rapidly within the cytoplasm and cell nucleus, the fibroblasts and glia cells are infected partly by the virus. Therefore, perhaps the neuron is the main harboring cell type.

Initiation of autoimmunity to the p53 tumor suppressor protein by complexes of p53 and SV40 large T antigen

Antinuclear antibodies (ANAs) reactive with a limited spectrum of nuclear antigens are characteristic of systemic lupus erythematosus (SLE) and other collagen vascular diseases, and are also associated with certain viral infections. The factors that initiate ANA production and determine ANA specificity are not well understood. In this study, high titer ANAs specific for the p53 tumor suppressor protein were induced in mice immunized with purified complexes of murine p53 and the Simian virus 40 large T antigen (SVT), but not in mice immunized with either protein separately. The autoantibodies to p53 in these mice were primarily of the IgG1 isotype, were not cross-reactive with SVT, and were produced at titers up to 1:25,000, without the appearance of other autoantibodies. The high levels of autoantibodies to p53 in mice immunized with p53/SVT complexes were transient, but low levels of the autoantibodies persisted. The latter may have been maintained by self antigen, since the anti-p53, but not the SVT, response in these mice could be boosted by immunizing with murine p53. Thus, once autoimmunity to p53 was established by immunizing with p53/SVT complexes, it could be maintained without a requirement for SVT. These data may be explained in at least two ways. First, altered antigen processing resulting from the formation of p53/SVT complexes might activate autoreactive T helper cells specific for cryptic epitopes of murine p53, driving anti-p53 autoantibody production. Alternatively, SVT-responsive T cells may provide intermolecular-intrastructural help to B cells specific for murine p53. In a second stage, these activated B cells might themselves process self p53, generating p53-responsive autoreactive T cells. The induction of autoantibodies during the course of an immune response directed against this naturally occurring complex of self and nonself antigens may be relevant to the generation of specific autoantibodies in viral infections, and may also have implications for understanding the pathogenesis of ANAs in SLE. In particular, our results imply that autoimmunity can be initiated by a "hit and run" mechanism in which the binding of a viral antigen to a self protein triggers an immune response that subsequently can be perpetuated by self antigen.

Characterization of vascular postsynaptic NPY receptor function and regulation and differential sensitivity of Y1 and Y2 receptor function to changes in extracellular calcium availability and prior in vitro peptide exposure

Effects of calcium-free buffer, nifedipine, or prior cumulative neuropeptide Y (NPY) receptor agonist concentration exposure on vasoconstrictive responsiveness to the agonists were assessed in norepinephrine (NE)-conditioned isolated rat femoral artery rings. Calcium-free buffer and nifedipine partially inhibited responsiveness to initial NPY exposure; residual responsiveness to NPY re-exposure was unaffected. In contrast, these treatments markedly inhibited responsiveness to the Y2 agonist NPY13-36, the calcium channel agonist BAY K 8644 (BAY) and the partial alpha 1 adrenoceptor agonist indanidine but did not alter to the Y1 agonist [Leu31,Pro34]NPY. Responsiveness to NPY and NPY13-36 but not to BAY or indanidine was markedly reduced 120 min following conditioning regardless of prior ring exposure to the same peptide; only prior exposure reduced responsiveness to [Leu31,Pro34]NPY. Responsiveness changes to NPY at various times or after various numbers of NE and/or NPY exposures indicated that pre-exposure and time-related responsiveness reductions were discriminable and temporally unrelated to conditioning. Postsynaptic vascular Y2 receptor activation therefore accounts for the known sensitivity of NPY-induced pressor and vasoconstrictive actions to nifedipine. The 'time-dependent' loss of Y2 receptor function may also explain prior failures to observe postsynaptic arterial Y2 receptors in vitro.

Characterization of vascular postsynaptic neuropeptide Y receptor function and regulation. 1. NPY-induced constriction in isolated rat femoral artery rings is mediated by both Y1 and Y2 receptors: evidence from benextramine protection studies

Neuropeptide Y (NPY), a potent pressor agent and vasoconstrictor, is thought to contribute to the sympathetically mediated postsynaptic regulation of blood pressure primarily through activation of vascular Y1 rather than Y2 NPY receptors. However, data are available that conflict with this conclusion. In this article, the relative roles of postsynaptic Y1 and Y2 receptors as mediators of direct NPY-induced isolated rat femoral artery ring vasoconstriction were evaluated through use of selective Y1 and Y2 agonists, [Leu31, Pro34]NPY ([Leu, Pro]NPY) and NPY13-36 [NPY(13-36)], respectively, and the NPY receptor antagonist benextramine (BXT). NPY, [Leu, Pro]NPY and NPY(13-36) were equipotent as vasoconstrictors, and constriction induced by each peptide, but not by the calcium channel agonist BAY K 8644 (BAY), was almost completely blocked by 10 microM BXT. Each of the three peptides also induced self- and cross-desensitization and protection from BXT blockade, except that [Leu, Pro]NPY neither desensitized nor protected NPY(13-36)-associated responses. NPY also failed to protect [Leu, Pro]NPY- and NPY(13-36)-elicited constriction, and NPY(13-36) failed to provide self-protection, from BXT blockade. However, in these instances, as opposed to the [Leu, Pro]NPY-NPY(13-36) cross-protection experiments, the occurrence of protection was probably masked by the relatively large magnitude of desensitization concurrently induced by the protecting peptide. Taken together, the present findings suggest that NPY-induced rat femoral artery vasoconstriction is mediated by separate, BXT-sensitive, postsynaptic Y1 ([Leu, Pro]NPY-activated) and Y2 [NPY(13-36)-activated] receptors.

An Arabidopsis thaliana lipoxygenase gene can be induced by pathogens, abscisic acid, and methyl jasmonate

We isolated and characterized a 2.8-kb, full-length, Arabidopsis thaliana cDNA clone encoding a lipoxygenase. DNA sequence analysis showed that the deduced amino acid sequence of the Arabidopsis protein is 72 to 78% similar to that of legume seed lipoxygenases. DNA blot analysis indicated that Arabidopsis contains a single gene, LOX1, with appreciable homology to the cDNA clone. RNA blot analysis showed that the LOX1 gene is expressed in Arabidopsis leaves, roots, inflorescences, and young seedlings. LOX1 expression levels were highest in roots and young seedlings. In mature plants, LOX1 mRNA levels increased upon treatment with the stress-related hormones abscisic acid and methyl jasmonate and remained high for at least 96 h. Expression of the LOX1 gene was examined following infiltration of leaves with virulent (Psm ES4326) and avirulent (Pst MM1065) strains of Pseudomonas syringae. LOX1 mRNA levels were induced approximately 6-fold by both virulent and avirulent strains; however, the response to avirulent strains was much more rapid. Infiltration of leaves with Pst MM1065 resulted in maximal induction within 12 h, whereas maximal induction by Psm ES4326 did not occur until 48 h. When a cloned avr gene, avrRpt2, was transferred to Psm ES4326, LOX1 mRNA accumulated in a pattern similar to that observed for the avirulent strain Pst MM1065.

Synthesis of a phenyl beta-avobioside derivative of the disaccharide component of avoparcins

The synthesis of the phenyl beta-glycoside of avobiose, a disaccharide fragment present in the antibiotic avoparcin, is reported. It is based on glycosylation of phenyl 3,4,6-tri-O-benzyl-beta-D-glucopyranoside with 2,3,6-trideoxy-4-O-p-nitrobenzoyl-3-trifluoroacetamido-L-ribo-hex- 1-enitol, a fully protected glycal of L-ristosamine, in the presence of trimethylsilyl triflate.

[Isolation and identification of Leclercia adecarboxylate in clinical isolates in China]

1987, 3 strains of gram-negative straight rods were examined from 3 cases of patients with diarrhea. It's producing yellow pigment, fermentative metabolism of carbohydrates, oxidase test negative and motility with the help of peritrichous flagella. Through systematic biochemical identification, calculation of G+C mol% and homology of DNA/DNA, the species of Leclercia adecarboxylate are identified. While the susceptibility to certain antibiotics and the pathogenicity for white mice are tested, and relation of these microorganisms to clinical diarrhea is discussed.

[Homology study of leptospires by molecular hybridization]

Nick translation and random primer labelling method were applied to prepare three genomic DNA probes from Leptospira interrogans strain 017, Leptospira biflexa strain Patoc I and Leptonema illini strain 3055, and then hybridized with DNA of 17 strains leptospires from different genus, species, serogroup and serovar. The results showed no homology between Leptospira and Leptonema, and only a low degree of homology between L. interrogans and L. biflexa but it showed a high degree of homology among L. interrogans. The study also proved the possibility to establish a DNA probe prepared from a single leptospira strain to detect different serovars.

Induction of Arabidopsis defense genes by virulent and avirulent Pseudomonas syringae strains and by a cloned avirulence gene

We developed a model system to study the signal transduction pathways leading to the activation of Arabidopsis thaliana genes involved in the defense against pathogen attack. Here we describe the identification and characterization of virulent and avirulent Pseudomonas syringae strains that elicit disease or resistance symptoms when infiltrated into Arabidopsis leaves. The virulent and avirulent strains were characterized by determining growth of the pathogen in Arabidopsis leaves and by measuring accumulation of mRNA corresponding to Arabidopsis phenylalanine ammonia-lyase (PAL), beta-1,3-glucanase (BG), and chalcone synthase (CHS) genes in infected leaves. The virulent strain, P. syringae pv maculicola ES4326, multiplied 10(5)-fold in Arabidopsis leaves and strongly elicited BG1, BG2, and BG3 mRNA accumulation but had only a modest effect on PAL mRNA accumulation. In contrast, the avirulent strain, P. syringae pv tomato MM1065, multiplied less than 10-fold in leaves and had only a minimal effect on BG1, BG2, and BG3 mRNA accumulation, but it induced PAL mRNA accumulation. No accumulation of CHS mRNA was found with either ES4326 or MM1065. We also describe the cloning of a putative avirulence (avr) gene from the avirulent strain MM1065 that caused the virulent strain ES4326 to grow less well in leaves and to strongly elicit PAL but not BG1 and BG3 mRNA accumulation. These results suggest that the Arabidopsis PAL and BG genes may be activated by distinct signal transduction pathways and show that differences in plant gene induction by virulent and avirulent strains can be attributed to a cloned presumptive avr gene.

Synthesis of disaccharide fragments of dermatan sulfate

Condensation of crystalline methyl 2-azido-4,6-O-benzylidene-2-deoxy-beta-D-galactopyranoside with methyl (2,3,4-tri-O-acetyl-alpha-L-idopyranosyl bromide)uronate in dichloromethane, in the presence of silver triflate and molecular sieve, provided 54% of methyl 2-azido-4,6-O-benzylidene-2-deoxy-3-O-(methyl 2,3,4-tri-O-acetyl-alpha-L-idopyranosyluronate)-beta-D-galactopyranoside . The use of methyl (2,3,4-tri-O-acetyl-alpha-L-idopyranosyl trichloroacetimidate)uronate as glycosyl donor, in the presence of trimethylsilyl triflate, improved the yield to 68%. Regioselective opening of the benzylidene group with sodium cyanoborohydride followed successively by O-sulfation with the sulfur trioxide-trimethylamine complex, saponification, catalytic hydrogenolysis and selective N-acetylation gave the disodium salt of methyl 2-acetamido-2-deoxy-3-O-(alpha-L-idopyranosyluronic acid)-4-O-sulfo-beta-D-galactopyranoside. Condensation of methyl 2-azido-4,6-O-benzylidene-2-deoxy-beta-D-galactopyranoside with methyl (2,3,4-tri-O-acetyl-alpha-D-glucopyranosyl bromide)uronate in dichloromethane, in the presence of silver triflate and molecular sieve, gave methyl 2-azido-4,6-O-benzylidene-2-deoxy-3-O-(methyl 2,3,4-tri-O-acetyl-beta-D-glucopyranosyluronate)-beta-D-galactopryano side in 85% yield. The sequence already described then gave the disodium salt of methyl 2-acetamido-2-deoxy-3-O-(beta-D-glucopyranosyluronic acid)-4-O-sulfo-beta-D-galactopyranoside.

HPLC analysis of montanoa species for pharmacologically active constituents1

A reversed phase HPLC method was developed for the qualitative and quantitative analysis of selected biologically active diterpenoid constituents of methanolic and hot water extracts of some MONTANOA species.

Analysis of the individual regulatory components of the IncFII plasmid replication control system

Replication of the IncFII plasmid NR1 is controlled by regulating the amount of synthesis of the repA1 initiator protein at both the transcriptional and translational levels. We have examined mutations which have altered each of these levels of regulation, resulting in different plasmid copy numbers. The genes which encode each of the individual wild-type or mutant regulatory components from the replication control region of NR1 have been cloned independently into pBR322 vectors, and their effects in trans, either individually or in various combinations, on plasmid incompatibility, stability, copy number, and repA1 gene expression have been defined.

Regulation of transcription of the repA1 gene in the replication control region of IncFII plasmid NR1 by gene dosage of the repA2 transcription repressor protein

Transcription of the repA1 gene of the IncFII plasmid NR1 is initiated at two promoters in the replication control region. Transcription from the upstream promoter is constitutive at a low level, whereas transcription from the downstream promoter is regulated. The 5' end of the constitutively synthesized transcript also encodes the transcription repressor protein for the regulated downstream promoter. Therefore, the level of the repressor protein in the cell is gene dosage dependent. Using both lac gene fusions and quantitative hybridization methods, we have determined the in vivo relationship between the rate of transcription from the regulated promoter and the repressor protein concentration as a function of gene dosage. At the wild-type copy number of NR1, transcription from the regulated promoter is 96% repressed, but substantial derepression occurs when the copy number falls below the normal value. At or above the normal plasmid copy number, the basal level of repA1 mRNA is provided by transcription from the constitutive upstream promoter.

IncFII plasmid incompatibility product and its target are both RNA transcripts

The region of DNA coding for incompatibility (inc) and copy number control (cop) of the IncFII plasmid NR1 is transcribed in both the rightward and leftward directions. The rightward transcripts serve as mRNA for the repA1 protein, which is required for replication. A small, 91-base leftward transcript is synthesized from the opposite DNA strand and is complementary to a portion of the rightward mRNA near its 5' end. A 262-base-pair Sau3A restriction fragment that encodes the small leftward transcript, but does not include the rightward transcription promoters, was cloned into the vector pBR322 or pUC8. The same fragment was cloned from an Inc- mutant of NR1 that does not make the small leftward transcript. Transcription through the cloned fragments in these derivatives was under control of the tetracycline resistance gene in pBR322 or the lac promoter-operator in pUC8. In one orientation of the inserted DNA, a hybrid transcript containing rightward NR1 RNA sequences was synthesized. In the other orientation, a hybrid transcript containing leftward NR1 RNA sequences was synthesized. These plasmids were used to vary the intracellular levels of the rightward or leftward NR1 RNA transcripts and to test their effects in trans on various coresident derivatives of NR1. An excess of rightward NR1 RNA in trans stimulated expression of the essential repA1 gene and caused an increase in the copy number of a coresident NR1 plasmid. An excess of leftward NR1 RNA in trans inhibited the expression of the repA1 gene and lowered the coresident NR1 copy number, thereby causing incompatibility. A pBR322 derivative with no transcription through the cloned NR1 DNA had no effect in trans. These results suggest that the small leftward transcript is the incompatibility inhibitor of NR1 and that its target is the complementary portion of the rightward mRNA.