Complete genome analysis of enterovirus 71 isolated from an outbreak in Taiwan and rapid identification of enterovirus 71 and coxsackievirus A16 by RT-PCR

Hand, foot, and mouth disease (HFMD) and encephalomyelitis were two major clinical manifestations during the 1998 enterovirus 71 (EV71) epidemic in Taiwan. To investigate whether different clinical patterns were caused by alterations in EV71 genomes, the complete nucleotide sequences of four EV71 strains associated with HFMD or encephalomyelitis were compared. Among these viral strains, two or three nucleotide differences were found within the 5'-noncoding region, and two or four amino acid differences were found within the regions encoding viral polyproteins; however, none of these differences were correlated with either clinical manifestation. Because coxsackievirus A16 was another major causative agent of HFMD, a reverse transcription-polymerase chain reaction assay, with high sensitivity and specificity for identification of EV71 (both 100%) and coxsackievirus A16 (100 and 98.8%), was developed for the rapid differential identification of these two viruses in HFMD patients.

In vitro modified release of acyclovir from ethyl cellulose microspheres

The aim of this study was to demonstrate a sustained-release microparticulate dosage form for acyclovir via an in vitro study. Ethyl cellulose was selected as a model encapsulation material. All of the microspheres were prepared by an oil-in-water solvent evaporation technique. A 2(3) full factorial experiment was applied to study the effects of the viscosity of polymer, polymer/drug ratio, and polymer concentration on the drug encapsulation efficiency and the dissolution characteristics. The encapsulation efficiency of acyclovir in microspheres was in the range of 20.0-56.6%. Increase in the viscosity of ethyl cellulose and the ratio of CH2Cl2/ethyl cellulose increased drug encapsulation efficiency. The drug continuously released from microspheres for at least 12 h, and the release rate depended on the pH of the release medium. The sustained release characteristic was more prominent in the simulated intestine fluid than in the simulated gastric fluid. A faster release of drug was observed when a high viscosity polymer was used. The decomposition of acyclovir significantly decreased when encapsulated by ethyl cellulose, especially when stored at 37 and 50 degrees C.

Antibacterial activity of leaf essential oils and their constituents from Cinnamomum osmophloeum

The antibacterial activities of the essential oils from leaves of two Cinnamomum osmophloeum clones (A and B) and their chemical constituents were investigated in this study. The nine strains of bacteria, including Escherichia coli, Pseudomonas aeruginosa, Enterococcus faecalis, Staphylococcus aureus, Staphylococcus epidermidis, methicillin-resistant Staphylococcus aureus (MRSA), Klebsiella pneumoniae, Salmonella sp., and Vibrio parahemolyticus, were used in the antibacterial tests. Results from the antibacterial tests demonstrated that the indigenous cinnamon B leaf essential oils had an excellent inhibitory effect. The MICs (minimum inhibitory concentrations) of the B leaf oil were 500 microg/ml against both K. pneumoniae and Salmonella sp. and 250 microg/ml against the other seven strains of bacteria. Cinnamaldehyde possessed the strongest antibacterial activity compared to the other constituents of the essential oils. The MICs of cinnamaldehyde against the E. coli, P. aeruginosa, E. faecalis, S. aureus, S. epidermidis, MRSA, K. pneumoniae, Salmonella sp., and V. parahemolyticus were 500, 1000, 250, 250, 250, 250, 1000, 500, and 250 microg/ml, respectively. These results suggest that C. osmophloeum leaf essential oil and cinnamaldehyde are beneficial to human health, having the potential to be used for medical purposes and to be utilized as anti-bacterial additives in making paper products.

Acute angle-closure glaucoma resulting from spontaneous hemorrhagic retinal detachment in age-related macular degeneration: case reports and literature review

PURPOSE

Acute angle-closure glaucoma resulting from massive subretinal hemorrhage is a rare and catastrophic complication in age-related macular degeneration. Anticoagulant usage had been strongly correlated with this complication in previously reported cases.

METHODS

Four patients (4 eyes), 3 men and 1 woman, developed angle-closure glaucoma with diffuse subretinal hemorrhage and total hemorrhagic retinal detachment.

RESULTS

Serial funduscopic examinations and echographic studies in 2 eyes showed that the blood gradually accumulated in the subretinal space. It took more than 10 days for the bleeding to build up to bullous hemorrhagic retinal detachment and secondary glaucoma. Anti-glaucomatous agents were given and sclerotomy was performed in 3 of the 4 patients. Phthisical changes were observed subsequently in these 3 eyes. The eye that received early drainage of blood was an exception, and a small degree of residual acuity was retained. Three of the 4 patients had diabetes mellitus, and hypertension and vascular diseases were also present in the same 3 patients.

CONCLUSIONS

Diabetes mellitus might be a predisposing factor for the impaired hemostasis. Anti-glaucomatous agents were of no effect in the management of intraocular pressure. Sclerotomy and drainage of blood help control intraocular pressure and relieve ocular pain. Poor final visual acuity is inevitable. However, phthisical changes might be prevented with early sclerotomy and drainage of blood.

Altered expression of nuclear matrix proteins in etoposide induced apoptosis in HL-60 cells

The events of cell death and the expression of nuclear matrix protein (NMP) have been investigated in a promyelocytic leukemic cell line HL-60 induced with etoposide. By means of TUNEL assay, the nuclei displayed a characteristic morphology change, and the amount of apoptotic cells increased early and reached maximun about 39% after treatment with etoposide for 2 h. Nucleosomal DNA fragmentation was observed after treatment for 4 h. The morphological change of HL-60 cells, thus, occurred earlier than the appearance of DNA ladder. Total nuclear matrix proteins were analyzed by 2-dimensional gel electrophoresis. Differential expression of 59 nuclear matrix proteins was found in 4 h etoposide treated cells. Western blotting was then performed on three nuclear matrix acssociated proteins, PML, HSC70 and NuMA. The expression of the suppressor PML protein and heat shock protein HSC70 were significantly upregulated after etoposide treatment, while NuMA, a nuclear mitotic apparatus protein, was down regulated. These results demonstrate that significant biochemical alterations in nuclear matrix proteins take place during the apoptotic process.

Antimite activity of essential oils and their constituents from Taiwania cryptomerioides

Antimite activity of essential oils and their components obtained from Taiwania cryptomerioides Hayata heartwood against Dermatophagoides pteronyssinus (Trouessart) and Dermatophagoides farinae Hughes was investigated in this study. Results from antimite tests demonstrated that the essential oil extracted from T. cryptomerioides heartwood had miticidal activity against D. pteronyssinus and D. farinae with a mortality of 67.0 and 36.7% at the dosage of 12.6 microg/cm2 after 48 h. Alpha-cadinol possessed the strongest antimite activity compared with other components of the T. cryptomeioides heartwood essential oil. The rectified mortalities of D. pteronyssinus and D. farinae were 100% for alpha-cadinol at the dosage of 6.3 microg/cm2. The order of antimite activity of four dominant constituents was alpha-cadinol > T-muurolol > ferruginol > T-cadinol. Paired Student's t-tests showed that there were significant differences between the rectified mortality of alpha-cadinol, T-muurolol, ferruginol and that of T-cadinol at the dosage of 6.3 microg/cm2 after 48 h.

An outbreak of enterovirus 71 infection in Taiwan, 1998. II. Laboratory diagnosis and genetic analysis

BACKGROUND

An epidemic of enterovirus 71 (EV71) occurred in Taiwan from April to December of 1998, with two peaks, one in June and the other in October. Many enteroviruses were isolated in our laboratory from 258 cases during this outbreak. Approximately half of the enteroviruses isolated were EV71 and one fifth were coxsackievirus A16.

OBJECTIVES

To analyze laboratory findings in the EV71 epidemic of 1998 in Taiwan, various EV71 specimens in different cell lines were examined. In addition, genetic analysis of 5' non-coding region (NCR) was performed to analyze the strain variation in this outbreak.

RESULTS

The cytopathic effect induced by EV71 was observed 2-13 (mean of 4.5) days post-inoculation in Vero cells and 4-15 (mean of 6.6) days in green monkey kidney (GMK) cells inoculated with throat swabs. Of the total positive EV71 cases, virus was most frequently obtained from throat swabs (91.7%), less from stools (64.8%), and none from cerebral spinal fluid (CSF). Molecular analyses of EV71 by sequencing the 5' NCR of 34 strains obtained from different clinical categories and various geographic areas showed that their sequences differed (0-13 bp in 681 bp sequenced) by approximately 0-2%. The sequences of these isolates differed from EV71 prototype BrCr or MS strain by 17.5-19%, with the exception of two samples which exhibited nucleotide variation by only 8.9 and 8.2%, when compared to the MS strain.

CONCLUSION

EV71 was most frequently isolated from throat swab specimens in Vero cells. The molecular analyses of the 5' NCR of EV71 revealed that most isolates from this epidemic belonged to a group of closely related clones and only two were in a different group which was clustered with the EV71 MS strain.

Characterization of the roles of the 594-645 region in human endothelial nitric-oxide synthase in regulating calmodulin binding and electron transfer

It has been postulated that a segment (residues 594-645) inserted in the FMN subdomain of human endothelial nitric-oxide synthase (eNOS) plays a crucial role in controlling Ca(2+)-dependent CaM binding for eNOS activity. To investigate its functions, we expressed human eNOS in a baculovirus system with deletion of a 45-residue segment from this region (residues 594-606 and 614-645, designated as Delta45eNOS), and characterized the purified mutant enzyme. In contrast with wild-type eNOS, Delta45eNOS exhibited characteristics resembling inducible NOS (iNOS). It contained an endogenously bound CaM, which was essential in folding and stabilizing this mutant enzyme, and retained 60% of L-citrulline formation in 5 mM EGTA. We also produced four N-terminally truncated reductase domains with or without the 45-residue segment, and either including or excluding the CaM-binding sequence. Basal cytochrome c reductase activity of reductase domains without the 45-residue segment was up to 20 fold greater than that of corresponding insert-containing domains, and higher than CaM-stimulated activity of the wild-type enzyme. A series of mutants with smaller fragment deletion in this region such as Delta594-604, Delta605-612, Delta613-625, Delta626-634, Delta632-639, and Delta640-645 mutants were further characterized. The crude lysate of mutants Delta613-625 and Delta632-639 did not show activity in the presence of Ca(2+)/CaM, while other four mutants had activity comparable to that of WTeNOS. The purified Delta594-604 and Delta605-612 proteins had a 3-5-fold higher affinity for Ca(2+)/CaM, but their L-citrulline forming activity was still 80% dependent upon the addition of Ca(2+)/CaM. Both mutants exhibited a low level of the cytochrome c and ferricyanide reductase activities, which either did not respond to (Delta594-604) or slightly enhanced by (Delta605-612) the exogenous CaM. In contrast, activities of Delta626-634 and Delta640-645 like those of WTeNOS were largely Ca(2+)/CaM-dependent. Thus, our findings indicate that the N-terminal half of the 594-645 segment containing residues 594-612 plays a significant role in regulating Ca(2+)/CaM binding.

Effects of Asp-369 and Arg-372 mutations on heme environment and function in human endothelial nitric-oxide synthase

Eight polar amino acid residues in the putative substrate-binding region from Thr-360 to Val-379 in human endothelial nitric-oxide synthase (eNOS) (Thr-360, Arg-365, Cys-368, Asp-369, Arg-372, Tyr-373, Glu-377, and Asp-378) were individually mutated. Only two of these residues, Asp-369 and Arg-372, were found to be essential for enzyme activity. A further series of mutants was generated by replacing these two residues with various amino acids and the mutant proteins were expressed in a baculovirus system. Mutant eNOS had a very low L-citrulline formation activity with the exception of D369E and R372K, which retained 27% and 44% of the wild-type enzyme activity, respectively. Unlike the wild-type enzyme, all mutants except D369E, R372K, and R372M had a low spin heme (Soret peak at 416 nm). All the Asp-369 mutants had higher Kd values for L-arginine (1-10 mM) than wild-type eNOS (0.4 microM) and an unstable heme-CO complex, and except for D369E, had a very low (6R)-5,6,7, 8-tetrahydro-L-biopterin (BH4) content. In contrast, each of Arg-372 mutants retained a considerable amount of BH4, had a moderate reduction in L-arginine affinity, and had a more stable heme-CO complex. 1-Phenylimidazole did not bind to wild-type eNOS heme, but bound to all Asp-369 and Arg-372 mutants (Kd ranged from 10 to 65 microM) except R372K. Heme spin-state changes caused by binding of 3, 5-lutidine appeared to depend on both charge and size of the side chains of residues 369 and 372. Furthermore, all Asp-369 and Arg-372 mutants were defective in dimer formation. These results suggest that residues Asp-369 and Arg-372 in eNOS play a critical role in oxygenase domain active-site structure and activity.

Ca2+ signaling induced by sphingosylphosphorylcholine and sphingosine 1-phosphate via distinct mechanisms in rat glomerular mesangial cells

BACKGROUND

To elucidate the molecular mechanism underlying sphingosine 1-phosphate (S1P) and sphingosylphosphorylcholine (SPC) mediated signaling, we compared their effects with those of adenosine triphosphate (ATP) and angiotensin II (Ang II) on the cytosolic free Ca2+ concentration ([Ca2+]i), inositol 1,4, 5-trisphosphate (IP3) generation and arachidonic acid release in rat glomerular mesangial cells.

METHODS

The fluorescent Ca2+ indicator, Fura-2, was used to measure the [Ca2+]i changes in cultured rat glomerular mesangial cells either in suspension or attached to the coverslips.

RESULTS

SPC 5 microM, S1P 5 microM, ATP 100 microM and Ang II 90 nM all induced increases in the [Ca2+]i, and the effect showed marked homologous desensitization, while heterologous desensitization was less. After the initial exposure of the cells to SPC, the increase in [Ca2+]i induced by subsequent addition of ATP or Ang II was only reduced by about 14.3% and 4.8%, respectively. After the initial exposure to S1P, a greater reduction was seen (42. 1% and 47.7%, respectively). Both arachidonic acid release and IP3 generation were activated by all four agonists with an identical rank order of effectiveness of SPC >> S1P > ATP = Ang II; both were pertussis toxin-sensitive and cholera toxin-resistant. The arachidonic acid release induced by all four agonists showed identical susceptibility to removal of extracellular Ca2+, whereas IP3 generation displayed differential extracellular Ca2+ dependence. Only SPC-induced IP3 generation was highly sensitive to extracellular Ca2+ level, and this Ca2+ dependence was abolished after pretreatment of cells with arachidonyl trifluoromethyl ketone (AACOCF3), a phospholipase A2 inhibitor. Furthermore, the Mn2+ influx was markedly greater in SPC-stimulated cells than in either control or other agonist-stimulated cells, and was decreased by prior exposure of cells to AACOCF3. After phospholipase A2 was inhibited or in the absence of extracellular Ca2+, SPC displayed identical effectiveness as S1P on desensitizing the action of ATP or Ang II on the increase in [Ca2+]i. Conclusions. Our results indicate that all four agents primarily activate phospholipase C through their receptor occupancies, but that SPC alone also induces further significant Mn2+ influx and IP3 generation attributable to its primary stimulatory effect on arachidonic acid release. Thus, the heterologous desensitization to ATP or Ang II induced by SPC was less profound than that induced by S1P, since SPC induced a Ca2+ influx.

Determination of medrogestone in plasma by high-performance liquid chromatography

Interference with the UV absorbance of medrogestone by endogenous steroids in plasma was prevented by reacting plasma with oxalyl chloride. The reduction of interference was effective when oxalyl chloride was in the range 10-50 microl/ml plasma. Reaction of oxalyl chloride with plasma for 10 min could reduce interference approximately 5.5-fold, and there was no significant reduction after 30 min. The limit of quantitative concentration for medrogestone in HPLC was 1 ng/ml. The standard curves were linear with the correlation coefficient greater than 0.999 in the range of 1-30 ng/ml. The coefficients of variation of both intra- and inter-day mean values were <12% and <10% of the actual values, respectively. The developed method for plasma sample preparation and the evaluated HPLC condition were further applied to an in vivo pharmacokinetic study.

Cloning, expression and sequence analysis of the classical swine fever virus nucleocapsid protein

The DNA complementary to the 5'-terminal 1929 nucleotides of classical swine fever virus (CSFV; alias hog cholera virus, HCV) LPC vaccine strain RNA was cloned and sequenced. The sequence encompasses a 5'-noncoding region (NCR) of 264 nucleotides and an open reading frame (ORF) of 1665 nucleotides. The cloned sequence contains genes of four viral proteins, P23, nucleocapsid (core) protein, E0 and part of E1 proteins. Alignment of the 5'-terminal 1929 nucleotides of LPC strain with other strains of CSFV showed well conservation and a homology as high as 84-95% was found between these strains. The cDNA of CSFV-LPC core was cloned into an expression vector, and a fusion protein of 38.5 kDa was obtained which reacted strongly to CSFV antiserum. Purification of the core fusion protein was achieved by a single-step affinity chromatography and the purified product could be recognized by the sera of CSFV-infected swine in ELISA assay. Phylogenetic analysis of the 5'-terminal 1929 nucleotides between pestiviruses revealed that the 5'-end region seems to be suitable for differentiation of different strains of CSFV.

Effects of various imidazole ligands on heme conformation in endothelial nitric oxide synthase

We have evaluated the influence of a series of substituted imidazoles on the heme structure of endothelial nitric oxide synthase (eNOS). Optical, MCD, and EPR spectra reveal widely differing effects on heme spin state and geometry. 1-Substituted imidazoles always yield low-spin heme complexes, but the size of the 2- and 4-substituent influences their structural effects on the heme. Methyl substituents lead to low-spin complexes while the bulky phenyl group yields high-spin complexes. The only exception to this behavior is provided by 2-aminoimidazole. Although this compound has three functional groups which can serve as an axial ligand to the heme, its binding to eNOS leads to a pure high-spin complex. This result can only be interpreted as due to a direct binding of 2-aminoimidazole to the guanidine binding subdomain of L-arginine. MCD spectra also imply that an O-ligand is present in the low-spin resting eNOS, while EPR data reveal the presence of two low-spin heme complexes in resting eNOS and its imidazole complexes. EPR also distinguishes four different high-spin forms of eNOS generated by different imidazole analogues. This series of ligands promises to be useful in probing the subtle structural difference among the active sites of three NOS isozymes and in developing selective inhibitors to these important enzymes.

Mutation of Glu-361 in human endothelial nitric-oxide synthase selectively abolishes L-arginine binding without perturbing the behavior of heme and other redox centers

Nitric oxide (NO) and L-citrulline are formed from the oxidation of L-arginine by three different isoforms of NO synthase (NOS). Defining amino acid residues responsible for L-arginine binding and oxidation is a primary step toward a detailed understanding of the NOS reaction mechanisms and designing strategies for the selective inhibition of the individual isoform. We have altered Glu-361 in human endothelial NOS to Gln or Leu by site-directed mutagenesis and found that these mutations resulted in a complete loss of L-citrulline formation without disruption of the cytochrome c reductase and NADPH oxidase activities. Optical and EPR spectroscopic studies demonstrated that the Glu-361 mutants had similar spectra either in resting state or reduced CO-complex as the wild type. The heme ligand, imidazole, could induce a low spin state in both wild-type and Glu-361 mutants. However, unlike the wild-type enzyme, the low spin imidazole complex of Glu-361 mutants was not reversed to a high spin state by addition of either L-arginine, acetylguanidine, or 2-aminothiazole. Direct L-arginine binding could not be detected in the mutants either. These results strongly indicate that Glu-361 in human endothelial NOS is specifically involved in the interaction with L-arginine. Mutation of this residue abolished the L-arginine binding without disruption of other functional characteristics.

Spatial relationship between L-arginine and heme binding sites of endothelial nitric-oxide synthase

Binding of L-arginine and imidazole to the endothelial nitric-oxide synthase (eNOS) was characterized by direct heme spectral perturbation. L-Arginine is competitive with imidazole for binding to eNOS. Both equilibrium binding and kinetic binding were measured at 4 and 23 degrees C for these two ligands. Kd (imidazole) is 60 microM and 110 microM, kon (imidazole) is 2.5 x 10(5) M-1 s-1 and 1. 2 x 10(6) M-1 s-1, koff (imidazole) is 11.8 s-1 and 116 s-1 at 4 and 23 degrees C, respectively. Corresponding values for L-arginine are calculated from the data of binding competition with imidazole and computer modeling. Kd (L-arginine) is 0.5 microM and 2.0 microM, kon (L-arginine) is 2 x 10(5) M-1 s-1 and 8 x 10(5) M-1 s-1, koff (L-arginine) is 0.08 s-1 and 1.6 s-1 at 4 and 23 degrees C, respectively. It is suggested that binding of both ligands occurs through the same access channel to the heme site based on their similarly slow association rate constants. A series of potential heme ligands and amino acid analogs of L-arginine were evaluated for their binding and their effect on the heme structure. All ligands besides cyanide tested for binding inhibition are competitive with either L-arginine or imidazole. The space for the distal heme ligand was estimated to be approximately 6.3 x 6.7 A by three groups of rigid planar ligands: imidazole, pyridine, and pyrimidine. Results of the thiazole and amino acid ligand series permitted the conclusion that the guanidine group of L-arginine is critical for its binding affinity and its specific orientation relative to the heme. Such a specific conformation is essential for the oxygenase mechanism of eNOS.

Characterization of endothelial nitric-oxide synthase and its reaction with ligand by electron paramagnetic resonance spectroscopy

Electron paramagnetic resonance was used to characterize the heme structure of resting endothelial nitric-oxide synthase (eNOS), eNOS devoid of its myristoylation site (G2A mutant), and their heme complexes formed with 16 different ligands. Resting eNOS and the G2A mutant have a mixture of low spin and high spin P450-heme with widely different relaxation behavior and a stable flavin semiquinone radical identified by EPR as a neutral radical. This flavin radical showed efficient electron spin relaxation as a consequence of dipolar interaction with the heme center; P1/2 is independent of Ca2+-calmodulin and tetrahydrobiopterin. Seven of the 16 ligands led to the formation of low spin heme complexes. In order of increasing rhombicity they are pyrimidine, pyridine, thiazole, L-lysine, cyanide, imidazole, and 4-methylimidazole. These seven low spin eNOS complexes fell in a region between the P and O zones on the "truth diagram" originally derived by Blumberg and Peisach (Blumberg, W. E., and Peisach, J. (1971) in Probes and Structure and Function of Macromolecules and Membranes (Chance, B., Yonetani, T., and Mildvan, A. S., eds) Vol. 2, pp. 215-229, Academic Press, New York) and had significant overlap with complexes of chloroperoxidase. A re-definition of the P and O zones is proposed. As eNOS and chloroperoxidase lie closer than do eNOS and P450cam on the truth diagram, it implies that the distal heme environment in eNOS resembles chloroperoxidase more than P450cam. In contrast, 4-ethylpyridine, 4-methylpyrimidine, acetylguanidine, ethylguanidine, 2-aminothiazole, 2amino-4,5-dimethylthiazole, L-histidine, and 7-nitroindazole resulted in high spin heme complexes of eNOS, similar to that observed with L-arginine. This contrasting EPR behavior caused by families of ligands such as imidazole/L-histidine or thiazole/2-aminothiazole confirms the conclusion derived from parallel optical and kinetic studies. The ligands resulting in the low spin complexes bind directly to the heme iron, while their cognate ligands induce the formation of high spin complexes by indirectly perturbing the heme structure and excluding the original axial heme ligand in the resting eNOS (V. Berka, P.-F. Chen, and A. -L. Tsai (1997) J. Biol. Chem. 272, in press). The difference in EPR spectra of these high spin eNOS complexes, although subtle, are different for different homologs.

Endothelial nitric-oxide synthase. Evidence for bidomain structure and successful reconstitution of catalytic activity from two separate domains generated by a baculovirus expression system

A baculovirus system was used to express the oxygenase and reductase domains of human endothelial nitric-oxide synthase (ecNOS) as distinct proteins. The oxygenase domain (residues 1-491) was expressed using a vector containing a His6 tag at the N terminus. The purified oxygenase domain had an apparent molecular mass of approximately 54 kDa, and retained the ability to bind L-arginine and form the ferrous CO complex. The purified reductase domain (residues 492-1244) had an apparent molecular mass of approximately 82 kDa and retained the ability to catalyze NADPH-dependent cytochrome c reduction, which was enhanced 10-fold by the presence of Ca2+/calmodulin. Both purified domains exhibited immunoreactivity to rabbit anti-ecNOS IgG. The NOS activity was successfully reconstituted by mixing the two domains. These results demonstrate for the first time that the two domains of ecNOS are catalytically intact and can be reconstituted in vitro.

Cysteine 99 of endothelial nitric oxide synthase (NOS-III) is critical for tetrahydrobiopterin-dependent NOS-III stability and activity

Tetrahydrobiopterin (BH4) is an essential cofactor for all three isoforms of nitric oxide synthase (NOS). However, its binding sites and functional roles remain elusive. Here, we demonstrated that cys-99 of human endothelial NOS (ecNOS) is critical for BH4 involvement in NOS catalytic activity and stability. Mutation of cys-99 to alanine in ecNOS resulted in loss of catalytic activity which could be restored to the level of wild type by adding a high concentration of exogenous BH4 to the crude extract. Purified C99A mutant was unstable and its maximal activity was only about 20% of the purified wild type activity. Comparison of BH4 concentration-dependent citrulline formation between C99A and the wild type revealed that the BH4 concentrations required for generating half-maximal citrulline were 10-fold higher for C99A. Purified C99A had no detectable BH4 and had a reduced heme content when compared to the purified wild type, but retained the ability of forming CO-ferrous heme complex and had the same Km value for L-arginine (approximately 4 microM) as the wild type. These findings indicate that Cys-99 is critically involved in BH4 binding. Mutation of this residue leads to reduced affinity for BH4 and the resultant enzyme instability and irreversible heme loss.

Cysteine 184 of endothelial nitric oxide synthase is involved in heme coordination and catalytic activity

Nitric oxide synthase catalyzes the formation of an important messenger molecule, nitric oxide (NO). It is a P450-type hemoprotein, containing a cysteine thiolate as its proximal heme ligand, but the exact cysteine residue involved in heme coordination has not been identified. To locate this specific cysteine, we altered three potential cysteine residues (Cys-99, Cys-184, and Cys-441) to alanine residues in human endothelial nitric oxide synthase (eNOS) by oligonucleotide-directed mutagenesis and expressed the wild-type and mutant eNOSs in COS-1 and the baculovirus expression system. Mutation of Cys-235 to alanine was included to serve as a control. Mutation of Cys-184 resulted in a complete loss of NOS catalytic activity and abrogation of the formation of carbon monoxide (CO)-heme ferrous complex, which was detected on CO difference spectra as a distinct peak centered on 444-446 nm, without reduction in the quantity of eNOS protein. Mutation of Cys-99 also resulted in a loss of catalytic activity but did not eliminate the 444-446 nm peak. C441A and C235A mutants displayed considerable NOS activity and retained the CO-heme peak on CO-ferrous difference spectra. These results indicate that the cysteine 184 of human eNOS is most likely the proximal heme ligand.

T-cell antigen receptors in rheumatoid arthritis

Rheumatoid arthritis (RA) is a systemic disease of unknown etiology characterized by chronic inflammation mainly in the joints. Several lines of evidence suggest that T cells are involved in the pathogenesis of the disease. RA is associated with certain HLA-DR alleles. Studies analyzing T-cell receptor transcripts in RA have found biased or preferential usage of certain V alpha and/or V beta gene segments by T cells infiltrating the synovial membrane or extravasating into the synovial fluid compared to peripheral blood. In certain patients few T-cell antigen receptor (TCR) clones dominated the infiltrating T cells, suggesting that T cells from the synovial membrane or the synovial fluid comprise oligoclonal populations of T cells. However, other studies have found a polyclonal population of T cells. In interpreting these results the phase of the disease (early vs. late RA), the source of T cells and the limitations of the methods used in these studies should be taken into consideration. However, it appears that synovial T cells comprise oligoclonal populations of T cells and that there is a bias towards particular TCR gene segments, although a specific TCR gene segment in RA has not emerged.

Preferential rearrangements of the V gamma I subgroup of the gamma-chain of the T-cell antigen receptor to J gamma 2C gamma 2 gene segments in peripheral blood lymphocyte transcripts from normal donors

To investigate whether there are preferential VJC gene rearrangements of the gamma-chain of the human T-cell antigen receptor (TCR), we amplified and sequenced gamma-chain TCR transcripts from peripheral blood lymphocytes from adult normal donors. cDNA was synthesized from total RNA and amplified by the polymerase chain reaction (PCR) using 5' primers specific for either the V gamma I or the V gamma II subgroups of the gamma-chain of the TCR. The amplified cDNAs were then cloned and sequenced. The majority (approximately 83%) of the cDNAs employing V-I subgroup gene segments rearranged to J gamma 2 (J gamma 2.1 or J gamma 2.3) C gamma 2 gene segments. This was in contrast to the predominant rearrangement of the V gamma II subgroup (V gamma 9) to J gamma 1.2C gamma 1. The remaining 13% of the cDNAs employing V gamma I subgroup gene segments rearranged to J gamma 1.1C gamma 1 or J gamma 1.3C gamma 1. There was significant N diversity as well as imprecise joining at the VJ junction. gamma delta TCR utilizing the C gamma 1 gene segment are disulfide-linked, whereas those utilizing the C gamma 2 gene segment are non-disulfide-linked. These results demonstrate that peripheral blood gamma-chain transcripts exhibit preferential rearrangements of V gamma I subgroup gene segments to J gamma 2(2.1,2.3)C gamma 2 gene segments. By contrast, V gamma II subgroup (V gamma 9) transcripts exhibit rearrangements to J gamma 1.2C gamma 1.

Human hybridoma-derived suppressor factor 160 and transforming growth factor-beta are different molecules

We have previously identified a suppressor factor (SF), designated 160 constitutively produced by human T-T-cell hybridomas generated by fusing Con A-activated human peripheral blood lymphocytes from a normal donor with cells of the Jurkat tumor T-cell line (Hybridoma 8:127-151, 1989). The 160 SF inhibited in vitro proliferative responses to polyclonal activators and allogeneic cells, and immunoglobulin synthesis and secretion of human and mouse lymphocytes. We investigated whether the hybridoma-derived 160 SF and transforming growth factor-beta (TGF-beta) are distinct molecules. TGF-beta has been shown to inhibit a number of lymphocyte responses. In agreement with our previous findings, the 160 SF abrogated the proliferative responses of human peripheral blood mononuclear cells (PBMC) to mitogens and allogeneic cells in mixed lymphocyte culture. In contrast, TGF-beta, added to the PBMC cultures at the same time with the mitogen or the stimulating allogeneic cells, had no effect on the proliferative response. Acid treatment of the 160 SF completely abolished the 160 SF activity. In contrast, this treatment results in activation of the latent TGF-beta form to the active form, and acidification does not affect the function of existing active TGF-beta. A polyclonal anti-TGF-beta antibody did not detect TGF-beta by Western blotting in concentrated (10x) 160 SF preparations. In addition, the 160 SF did not induce the anchorage-independent growth of NRK fibroblasts in the presence of EGF.TGF-beta at concentrations as low as 1 ng/ml, in the presence of EGF, induced the anchorage-independent growth of the anchorage-dependent indicator NRK cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Development of the non-palindromic adaptor polymerase chain reaction (NPA-PCR) for the amplification of alpha- and beta-chain T-cell receptor cDNAs

We have developed a highly efficient new method for the amplification of alpha- and beta-chain human T-cell receptor (TCR) cDNAs. This method is designated non-palindromic adaptor polymerase chain reaction (NPA-PCR). cDNA was synthesized from total RNA isolated from mononuclear leucocytes, using either an oligo (dT)15-NotI or a C alpha-NotI or a C beta-NotI primer and RNase H-negative reverse transcriptase. The double-stranded cDNA was ligated with the non-palindromic adaptors EcoRI-XmnI [d(ATTCGAACCCCTTCG)] and XmnI G strand [d(pCGAAGGGGTTCG)] (phosphorylated), which resulted in the addition of the EcoRI-XmnI site in both 5' and 3' ends. These two non-palindromic adaptors, EcoRI-XmnI and XmnI G strand, are complementary to each other and both are required for ligation. The EcoRI-XmnI adaptor was removed from the 3' end by treatment with NotI restriction nuclease, whereas it was retained at the 5' end. The non-palindromic adaptor EcoRI-XmnI was used as the 5' amplification primer. C alpha or C beta constant region primers were used as 3' amplification primers. The amplified cDNAs were cloned and the plasmids were used to transform DH5 alpha competent cells. Over 1000 white colonies per 0.1-0.25 micrograms of total RNA or per 10,000 to 50,000 human peripheral blood mononuclear cells were obtained after amplification of either the alpha- or the beta-chain TCR cDNAs. Between 40 and 62% of the colonies (range from five donors) were positive after screening with either a C alpha or a C beta probe, located 5' to the C alpha and C beta amplification primers. A total of 50 amplified alpha- or beta-chain cDNA positive clones from two normal donors were randomly chosen and sequenced, and the sequences obtained were typical of alpha beta TCR. Two new J alpha gene segments were identified. Approximately 30% of the alpha-chain positive clones have 5' untranslated region, and most of the remaining alpha- or beta-chain TCR clones started from the initiation codon or near the 5' end. NPA-PCR has several advantages over existing PCR methods for the amplification of cDNAs with unknown or variable 5' end, such as the T-cell antigen receptors and the immunoglobulins. Among these advantages is that only one 5' end extension primer is required. Because of the large number of TCR V alpha and V beta families, a large number of different 5' end primers are required for amplification of alpha beta TCR cDNAs by conventional PCR.

Gamma/delta T cell antigen receptors expressed on tumor-infiltrating lymphocytes from patients with solid tumors

The expression of gamma/delta T cell antigen receptors (TcR) in T cell lines or clones derived from tumor-infiltrating lymphocytes (TIL) from patients with solid tumors was investigated. gamma/delta TcR T cell lines were derived from TIL from patients with Wilms tumor, sarcoma or metastatic melanoma by stimulation with autologous tumor cells alone and recombinant interleukin 2 and they exhibited nonspecific cytotoxicity against autologous and allogeneic tumor cells, or cells of the K562 or the MEL21 tumor cell lines. Two T cell lines were derived from a patient with Wilms tumor. One of them expressed a non-disulfide-linked gamma/delta TcR using the 60-kDa gamma chain, whereas, the other expressed a disulfide-linked gamma/delta TcR. A T cell line was derived from a patient with sarcoma and expressed a disulfide-linked gamma/delta TcR, whereas, a T cell line derived from a patient with melanoma expressed a non-disulfide-linked gamma chain of 62 kDa. Several T cell clones were developed from patients with metastatic melanoma or Wilms tumor and expressed either disulfide- or non-disulfide-linked gamma/delta TcR. Northern analysis of RNA from certain of these clones revealed a full-length gamma chain transcript, whereas, the alpha or beta chain transcripts were either absent or truncated. These T cell clones exhibited nonspecific cytotoxicity. Both disulfide- and non-disulfide-linked TIL T cell lines and clones expressed the delta TCS1 determinant. gamma/delta TcR+ cells in freshly prepared TIL from these patients were present in low proportions (less than 5%) and their delta TCS1/delta 1 ratios were within the range observed in the peripheral blood of normal donors. These results demonstrate that both disulfide- and non-disulfide-linked gamma/delta TcR are expressed on T cell lines and clones derived from TIL from solid tumors. Non-disulfide-linked gamma/delta TcR using the 56-66-kDa gamma chain are frequently found on TIL-derived T cell lines and clones. These 56-66-kDa gamma chains are rarely expressed on T cell lines or clones derived from peripheral blood lymphocytes of normal donors.

IL-2-dependent murine T-cell lines and clones expressing gamma/delta T-cell antigen receptors. I. Functional and biochemical characterization

We have developed two stable IL-2-dependent T-cell lines designated AKV-I and AKV-N from the enlarged spleens, respectively, of an AKV1 and an NFS mouse. Immunofluorescence staining with the appropriate monoclonal antibodies revealed that cells of the AKV-I cell line were alpha beta TCR-CD3+CD4-CD5-CD8+CD25+, whereas cells of the AKV-N cell line were alpha beta TCR-CD3+CD4-CD5+CD8-CD25+. A number of T-cell clones were developed from the AKV-I or AKV-N T-cell lines by limiting dilution and analysed by immunofluorescence. All clones tested were alpha beta TCR-CD3+CD4-CD25+. Certain T-cell clones expressed the CD5 antigen, whereas others expressed the CD8 antigen. The AKV-I cell line responded by proliferation to rIL2, rIL4, phorbol myristate acetate (PMA), PMA plus IL-4 and PMA plus PHA or Con A. In contrast, the AKV-N cell line did not respond to rIL-4 or rIL-4 plus PMA and exhibited only a modest proliferative response to PMA alone. Both AKV-I and AKV-N T-cell lines as well as a large number of T-cell clones examined were able to lyse cells of the PU5-IR murine cell line in the presence of the anti-CD3 (clone 145-2C11) MoAb, demonstrating their ability to mediate cytotoxicity in this system. Biochemical analysis of both AKV lines and a number of clones by immunoprecipitation with the anti-CD3 MoAb, followed by one-dimensional (either non-reducing or reducing) or two-dimensional (non-reducing/reducing) SDS-PAGE, revealed that the AKV lines and clones expressed a disulphide-linked dimer. Under non-reducing conditions, a band in the range of 75-85 kDa was observed and upon reduction it was resolved into two discrete polypeptide chains of 43-44 kDa and 48 kDa in certain AKV-I cells or 38 kDa and 42 kDa in certain AKV-N cells. In other T-cell clones or lines a broad band of 42-47 kDa was observed in AKV-I cells or 38-45 kDa in AKV-N cells. These results suggest the presence of different forms of disulphide-linked dimers on these cells. Northern blotting analysis using probes specific for the constant regions of the alpha-, beta-, gamma- and delta-chains of the T-cell antigen receptor revealed that all the AKV cell lines or clones tested expressed full-length alpha-, gamma- and delta-chain mRNA, whereas beta-chain mRNA was absent.(ABSTRACT TRUNCATED AT 250 WORDS)