Interaction between the tobacco mosaic virus movement protein and host cell pectin methylesterases is required for viral cell-to-cell movement

Virus-encoded movement protein (MP) mediates cell-to-cell spread of tobacco mosaic virus (TMV) through plant intercellular connections, the plasmodesmata. The molecular pathway by which TMV MP interacts with the host cell is largely unknown. To understand this process better, a cell wall-associated protein that specifically binds the viral MP was purified from tobacco leaf cell walls and identified as pectin methylesterase (PME). In addition to TMV MP, PME is recognized by MPs of turnip vein clearing virus (TVCV) and cauliflower mosaic virus (CaMV). The use of amino acid deletion mutants of TMV MP showed that its domain was necessary and sufficient for association with PME. Deletion of the PME-binding region resulted in inactivation of TMV cell-to-cell movement.

[Induction of fluoride-resistant mutant of S. mutans and the measurement of its acidogenesis in vitro]

OBJECTIVE

To induce fluoride-resistant mutant of S. mutans in vitro and find out the differences of cariogenicity between them.

METHODS

Fluoride-resistant strain Ingbritt-FR was obtained by subculturing S. mutans Ingbritt to TSA and TSB containing different concentrations of fluoride. Lactic production and terminal pH of media were measured by gas chromatography method.

RESULTS

1. The stable fluoride-resistant mutant of S. mutans Ingbritt had been induced successfully in vitro; 2. Lactic production of Ingbritt-FR was significantly more than its parent strain at various initial pH values with 0.5 and 5.0 mmol/L fluoride whereas when no fluoride existed, there were two situations: the acid production was more than S. mutans Ingbritt at initial pH above 5.0 while the result was opposite when pH was 5.0 and below.

CONCLUSION

The fluoride-resistant strain Ingbritt-FR had a stronger cariogenic potential than its parent strain S. mutans Ingbritt in physiological plaques.

Dehydration behavior of eprosartan mesylate dihydrate

Eprosartan mesylate (SKF 108566-J; EM) is an antihypertensive agent approved for marketing in the USA. EM dihydrate was prepared by three methods, one of which included suspending the anhydrous drug in an aqueous solution of 1.0 M methanesulfonic acid to form a slurry, followed by filtration. The dehydration kinetics of EM dihydrate were derived by analyzing the fit of the isothermal thermogravimetric analytical (TGA) data to numerous kinetic models. EM dihydrate undergoes dehydration in two distinct steps, each involving the loss of 1 mol of water at 25-70 degrees C and 70-120 degrees C, respectively. Recrystallization of EM occurs at approximately 120-140 degrees C after dehydration to the anhydrous phase. This explanation is supported by variable temperature powder X-ray diffractometry. The mechanism of the dehydration reaction is complex, the dependence of the reaction rate on temperature varying as a function of the particles size. For the dihydrate of sieve fraction <125 microm, the kinetics of the first and second dehydration steps are consistent with the Avrami-Erofeev equation (A3, n = 1/3) over the temperature range studied, corresponding to three-dimensional growth of nuclei. In contrast, for the 125-180-microm and 180-250-microm sieve fractions, the kinetics are best described by the two-dimensional phase boundary reaction (R2) at a lower dehydration temperature (i.e., 28.3 degrees C), and by the Avrami-Erofeev equation (A3, n = 1/3) at a higher dehydration temperature (i.e., 93.7 degrees C). The activation energies (15-40 kcal/mol) and frequency factors of the dehydration of EM dihydrate were determined both by Arrhenius plots of the isothermal rates determined by TGA and by Kissinger plots of the nonisothermal differential scanning calorimetric data. Hot stage microscopy of single crystals of EM dihydrate showed random nucleation at the surface and dehydration with the growth of microcrystals along the needle a axis. Cerius(2) molecular modeling software showed the existence of water channels along the a axis and enabled the observed dehydration behavior of EM dihydrate crystals to be explained in terms of the bonding environment of water molecules in the crystal structure.

A G1 cell cycle arrest induced by ligands of the reovirus type 3 receptor is secondary to inactivation of p21ras and mitogen-activated protein kinase

The reovirus type 3 S1 gene product (type 3 hemagglutinin; HA3) is the viral protein responsible for binding to a mammalian cell-surface receptor. It has been shown that HA3 binding to its receptor inhibits cell growth, even in the continuous presence of serum mitogens. Here, receptor-mediated signal transduction leading to growth arrest was studied after binding with synthetic or recombinant ligands in the absence of viral infection. Receptor ligation caused rapid inactivation of p21(ras), a decrease in Raf phosphorylation and in mitogen-activated protein kinase (MAPK) enzymatic activity, and G1 cell cycle arrest. Transfection and expression of constitutively active v-Has-ras prevented the G1 arrest, indicating that inactivation of p21(ras) is causative. Interestingly, v-Has-ras expression also decreased the efficiency of reoviridae replication, suggesting that inactivation of p21(ras) signals is required at some step of the viral cycle. This study may define new mechanisms regulating cell growth and support the approach of using viral proteins to identify and study cellular receptors. Synthetic receptor ligands with antiproliferative properties may be useful in drug development with the aim of blocking mitosis.

Failure and complication following surgical treatment of scoliosis--an analysis of 101 cases

Complications occur frequently after surgical treatment of scoliosis. In order to prevent from them effectively, 101 cases with failure and postoperative complications were analysed. They included rod fracture in 22 cases (15 Harrington rods, 4 Zielke rods, and 3 Luque rods); recurrence of curve severity in 12 cases; broken or loossened luque wires in 15 cases; loss of thoracic kyphosis (flat back) in 6 cases; progressive kyphosis with or without paraplegia following incorrect posterior decompression in 5 cases; and increased unbalance of shoulders after instrumentation in 2 cases due to neglect of the tilting of the first thoracic vertebra. Infection occurred in 8 cases (incision infection 7 cases, deep wound infection in 1 case); and pneumothorax in 1 case. They were induced by biomechanical factors in 23 cases (22.8%), incorrect selections of indications in 29 cases (28.7%), operational mistakes in 37 cases (36.6%), internal fixation factors in 15 cases (14.9%). The authors hold that there are quite a lot of factors leading to occurrence of complications and the effective way for prevention from them is to understand the factors and main technical points related to internal fixation.

An Arabidopsis thaliana mutant with virus-inducible phenotype

The role of host factors in plant viral diseases is not well understood. To study this important aspect of plant-pathogen interaction, we identified an Arabidopsis thaliana mutant, designated vid1 (virus-inducible dwarf), with altered responses to viral infection. Specifically, vid1 resembled the wild-type plants when healthy but developed a severely dwarfed phenotype with a loss of apical dominance following infection by a tobamovirus. Genetic segregation showed that the vid1 phenotype is caused by a recessive mutation in a single gene. Since systemic viral infection is thought to interfere with the host plant intercellular transport, we propose that the vid1 mutation affects this transport process. Combination of the mutation and viral infection may disrupt transport of developmental regulators, such as hormones, causing formation of the vid1 phenotype. Indeed, the effect of vid1 mutation was repressed by exogenous application of a plant hormone auxin. Potentially, the vid1 mutant will help characterize the mechanism of virus-plant interaction and formation of plant viral disease symptoms.

[Study on method of sampling and analysis of trichloroaniline in the air]

Trichloroaniline in the air was collected with 50% ethanol and separated with a column OV-17:OV-210 ECD as a detector. The best conditions of sampling and determining were selected through the orthogonal experimental design. The detectable limit was 0.01 mg/L. When the concentration of trichloroaniline in the air was 0.5-10 mg/L, the relative standard deviation (RSD) was 4.3%-3.7%. There was a linear relation within the range of 0.02-40 mg/L. The sampling efficiency was 99.1%-100%. The samples were stable for at least 15 days. It is proved that this method is accurate, fast, simple and sensitive. It is suitable for the determination of trichloroaniline in the air.

Adenoviral vector-mediated GDNF gene therapy in a rodent lesion model of late stage Parkinson's disease

A recombinant adenoviral vector encoding the human glial cell line-derived neurotrophic factor (GDNF) gene (Ad-GDNF) was used to express the neurotrophic factor GDNF in the unilaterally 6-hydroxydopamine (6-OHDA) denervated substantia nigra (SN) of adult rats ten weeks following the 6-OHDA injection. 6-OHDA lesions significantly increased apomorphine-induced (contralateral) rotations and reduced striatal and nigral dopamine (DA) levels by 99% and 70%, respectively. Ad-GDNF significantly (P < 0.01) decreased (by 30-40%) apomorphine-induced rotations in lesioned rats for up to two weeks following a single injection. Locomotor activity, assessed 7 days following the Ad-GDNF injection, was also significantly (P < 0.05) increased (by 300-400%). Two weeks after the Ad-GDNF injection, locomotor activity was still significantly increased compared to the Ad-beta-gal-injected 6-OHDA lesioned (control) group. Additionally, in Ad-GDNF-injected rats, there was a significant decrease (10-13%) in weight gain which persisted for approximately two weeks following the injection. Consistent with the behavioral changes, levels of DA and the metabolite dihydroxyphenylacetic acid (DOPAC) were elevated (by 98% and 65%, respectively) in the SN, but not the striatum of Ad-GDNF-injected rats. Overall, a single Ad-GDNF injection had significant effects for 2-3 weeks following administration. These results suggest that virally delivered GDNF promotes the recovery of nigral dopaminergic tone (i.e.: increased DA and DOPAC levels) and improves behavioral performance (i.e.: decreased rotations, increased locomotion) in rodents with extensive nigrostriatal dopaminergic denervation. Moreover, our results suggest that viral delivery of trophic factors may be used eventually to treat neurodegenerative diseases such as Parkinson's disease.

Arginine294 is essential for the inhibition of Anabaena PCC 7120 ADP-glucose pyrophosphorylase by phosphate

Treatment of ADP-glucose pyrophosphorylase (EC 2.7.7.27) from the cyanobacterium Anabaena PCC 7120 with phenylglyoxal in 50 mM Hepes, pH 8.0, at 25 degrees C resulted in a time- and concentration-dependent loss of enzyme activity. Phosphate, the inhibitor, protected the enzyme from inactivation most effectively, while 3-P-glycerate, fructose-1,6-P2, pyridoxal-P, and ATP plus magnesium were also good protectors. After incubation with 2 mM phenylglyoxal for 1 h, the modified enzyme had a 10-fold lower apparent affinity for phosphate in the absence of the activator, 3-P-glycerate, than that of the wild-type enzyme. This result has implicated the involvement of an arginine residue at the allosteric sites, most probably the inhibitor-binding site, of ADP-glucose pyrophosphorylase from the cyanobacterium Anabaena PCC 7120. In order to identify the arginine residue, five arginine residues, which are conserved in all higher-plant and cyanobacterial enzymes but not in enteric bacterial enzymes, were individually converted to alanine by site-directed mutagenesis. The mutant enzymes, R66A, R105A, R294A, and R385A, were purified, and the properties of these mutants were compared with the wild-type enzyme. Substitution of arginine294 with alanine resulted in an enzyme with more than 100-fold or 40-fold lower affinity for the inhibitor, phosphate, in the absence or presence of 3-P-glycerate, respectively. This mutation had no or lesser impact on the kinetic constants for the substrates and the activator, 3-P-glycerate.

Site-directed mutagenesis of lysine382, the activator-binding site, of ADP-glucose pyrophosphorylase from Anabaena PCC 7120

Previous studies have shown that a highly conserved lysyl residue (Lys 419) near the C-terminus of Anabaena ADP-glucose pyrophosphorylase is involved in the binding of 3-P-glycerate, the allosteric activator [Charng, Y., Iglesias, A. A., & Preiss, J. (1994) J. Biol. Chem. 269, 24107-24113]. Phosphopyridoxylation of the K419R mutant enzyme modified another conserved lysyl residue (Lys382), suggesting that this residue might be also located within the activator-binding site [Charng, Y., Iglesias, AA., & Preiss, J. (1994) J. Biol. Chem. 269, 24107-24113]. Site-directed mutagenesis of Lys382 of the Anabaena enzyme was performed to determine the role of this residue. Replacing Lys382 with either arginine, alanine, or glutamine produced mutant enzymes with apparent affinities for 3-P-glycerate 10-160-fold lower than that of the wild-type enzyme. The glutamic acid mutant enzyme was inhibited by 3-P-glycerate. These mutations had lesser impact on the kinetic constants for the substrates and inhibitor, P(i), and on the thermal stability. These results indicate that both the charge and size of the residue at position 382 influence the binding of 3-P-glycerate. Site-directed mutagenesis was also performed to obtain a K382R-K419R double mutant. The apparent affinity for 3-P-glycerate of this double-mutant enzyme was 104-fold lower than that of the wild-type enzyme, and the specificity for activator of this mutant enzyme was altered. The K382R-K419R enzyme could not be phosphopyridoxylated, suggesting that other lysine residues are not involved in the binding of 3-P-glycerate.

Detection by polymerase chain reaction of wild-type measles virus genome in the cerebrospinal fluid of a patient with SSPE who had received measles vaccine

BACKGROUND

Previous studies have reported that approximately 4-5% of patients with subacute sclerosing panencephalitis (SSPE) were given measles vaccination but had no history of natural measles. However, in the case who received measles vaccine, it has been extremely difficult to determine whether the actual cause of SSPE is the inoculated vaccine virus or not.

OBJECTIVES

To detect the measles virus genome in a patient with SSPE and to analyze its nucleotide and deduced amino acid sequence.

STUDY DESIGN

We applied the polymerase chain reaction (PCR) to detect the measles virus genome in specimens from a 12-year-old boy with SSPE who had received measles vaccine 10 years before and had no history of apparent natural measles. The oligonucleotide primers for PCR were prepared based on the nucleotide sequence of the F and NP genes of the measles virus Edmonston strain.

RESULTS

F and NP genes were detected in both the cerebrospinal fluid and peripheral blood lymphocytes. Nucleotide and deduced amino acid sequence analysis of the F gene showed that the patient's virus was different from that of the vaccine strain. Judging from these results, it was likely that the SSPE-associated strain in this case was derived from the wild-type rather than the vaccine strain.

CONCLUSIONS

PCR is a useful method to establish a definitive diagnosis of SSPE and to study the nature of the SSPE-associated virus.

Identification of human genes related to olfactory-specific CYP2G1

CYP2G1, which is uniquely expressed in the olfactory mucosa of rats and rabbits, may have functions important for the olfactory chemosensory system. The aim of the present study is to determine whether CYP2G genes are present in the human genome. Several gene fragments were obtained by PCR amplification of human genomic DNA. One fragment, termed E7, which contained an open reading frame for 44 amino acids, is highly homologous in deduced amino acid sequence to residues 322-375 in rabbit or rat CYP2G1. Three other gene fragment, termed E7-8, H2Gp1 and H2Gp2, respectively, were also obtained and found to have structural homology with coding sequences in the rat CYP2G1 gene. RNA-PCR analysis of human nasal RNA indicated that at least one CYP2G gene is transcribed. Southern blot analysis of human genomic DNA with use of cloned E7 or E7-8 as the probe indicated that more than one CYP2G-related gene may be present in the human genome. These results provide a basis for further characterization of the structure and function of the human CYP2G genes.

Delayed activation of altered fusion glycoprotein in a chronic measles virus variant that causes subacute sclerosing panencephalitis

We compared the intracellular processing of the fusion (F) glycoproteins of an acute measles virus (MV) Nagahata strain and its relative Biken strain that caused subacute sclerosing panencephalitis (SSPE), Nagahata strain synthesizes a precursor F0 which acquires three asparagine (N)-linked oligosaccharide chains sequentially in 1 h. One oligosaccharide chain on the partially glycosylated F0 is less accessible to endo-beta-N-acetylglucosaminidase H (endo-H) but becomes accessible as the protein becomes fully glycosylated, suggesting a protein conformational change. Biken strain SSPE virus synthesizes a similarly glycosylated F0. However, one oligosaccharide chain on the Biken F0 remains less accessible to endo-H even after the protein is fully glycosylated. The Nagahata F0 is cleaved into the F1 and F2 subunits with a half life of 1 h. The Biken F0 is cleaved with a half life of 4 h. We cloned the F genes of Nagahata and Biken strains and showed by transfection that the defect causing delayed cleavage of F0 resides in the Biken F gene. Sequence analysis predicts a mutation in the cleavage recognition sequence, a truncated carboxyl-terminus, and multiple mutations in F1 of the Biken F protein. Expression of chimeric F genes showed the mutated cleavage recognition sequence and the carboxyl-terminal truncation do not delay cleavage of F0. Instead, delayed F0 cleavage is due to multiple mutations in the extracellular domain of F1, and four amino acid substitutions near the transmembrane region impair endo-H access to the oligosaccharide chain. These results provide detailed information on the normal maturation process of the F protein of MV and additional clues to the mechanisms of MV persistence in the CNS.

Cryo atomic force microscopy: a new approach for biological imaging at high resolution

A low-temperature atomic force microscope (cryo-AFM), operated in liquid nitrogen vapor, has been constructed for biological applications. The system provides an adjustable imaging temperature from 77 to 220 K with atomic resolution achieved on crystalline specimens. Imaging with NaCl microcrystals demonstrates that the system is free from surface contamination. Below 100 K, several biological specimens, including immunoglobulins and DNA as well as red blood cell ghosts, were imaged at high spatial resolution. Measurements on individual macromolecules showed that the mechanical strength is significantly greater at cryogenic temperatures with an estimated Young's modulus 1000-10,000 times that of a hydrated protein at room temperature, providing a solid basis for future improvements and applications of cryo-AFM in structural biology.

Delayed activation of altered fusion glycoprotein in a chronic measles virus variant that causes subacute sclerosing panencephalitis

We compared the intracellular processing of the fusion (F) glycoproteins of an acute measles virus (MV) Nagahata strain and its relative Biken strain that caused subacute sclerosing panencephalitis (SSPE). Nagahata strain synthesizes a precursor F0 which acquires three asparagine (N)-linked oligosaccharide chains sequentially in 1 h. One oligosaccharide chain on the partially glycosylated F0 is less accessible to endo-beta-N-acetylglucosaminidase H (endo-H) but becomes accessible as the protein becomes fully glycosylated, suggesting a protein conformational change. Biken strain SSPE virus synthesizes a similarly glycosylated F0. However, one oligosaccharide chain on the Biken F0 remains less accessible to endo-H even after the protein is fully glycosylated. The Nagahata F0 is cleaved into the F1 and F2 subunits with a half life of 1 h. The Biken F0 is cleaved with a half life of 4 h. We cloned the F genes of Nagahata and Biken strains and showed by transfection that the defect causing delayed cleavage of F0 resides in the Biken F gene. Sequence analysis predicts a mutation in the cleavage recognition sequence, a truncated carboxyl-terminus, and multiple mutations in F1 of the Biken F protein. Expression of chimeric F genes showed the mutated cleavage recognition sequence and the carboxyl-terminal truncation do not delay cleavage of F0. Instead, delayed F0 cleavage is due to multiple mutations in the extracellular domain of F1, and four amino acid substitutions near the transmembrane region impair endo-H access to the oligosaccharide chain. These results provide detailed information on the normal maturation process of the F protein of MV and additional clues to the mechanisms of MV persistence in the CNS.

Mutagenesis of an amino acid residue in the activator-binding site of cyanobacterial ADP-glucose pyrophosphorylase causes alteration in activator specificity

The specificity for activator of ADP-glucose pyrophosphorylase is closely related to the corresponding major carbon-assimilation pathway. The enzyme from Escherichia coli is mainly activated by fructose-1,6-P2, while the cyanobacterial, algal, and higher-plant enzymes are activated by 3-P-glycerate. Previous results have shown that Lys39 of the E. coli enzyme is involved in the binding of fructose-1,6-P2 while for the Anabaena enzyme, lysine residues 382 and 419 have been shown to be involved in the binding of 3-phosphoglycerate. This report shows that if Lys419 of the Anabaena enzyme is changed to glutamine, activation of the cyanobacterial enzyme by fructose-1,6-P2 becomes more effective than that of 3-P-glycerate at lower concentrations. Kinetic studies show that fructose-1,6-P2 competitively inhibits 3-P-glycerate activation of the Anabaena wild-type enzyme, suggesting that these two compounds bind to the same site. Thus a change of one amino acid at the activator binding domain can affect the specificity of activation of the Anabaena ADP-glucose pyrophosphorylase.

Conformational changes of proteins at an interface induced by a supported planar phosphatidic acid monolayer

Conformational changes of two types of proteins, water-soluble proteins (BSA and myoglobin) and membrane-associated protein (cytochrome c), induced by a negatively charged supported planar phospholipid monolayer were studied. The water-soluble proteins lost most of their ordered secondary structure and formed a random conformation in the initial stage of adsorption, and but in the later stage they retained more of the alpha-helical structure which was their main native secondary structure in solution. The membrane-associated protein, cytochrome c, showed a different conformational change in the adsorption process. In the initial stage, it showed an increase in beta-structures but not random coils. In the later stage, it contained more alpha-helixes than that in solution.

A 6-hydroxydopamine-induced selective parkinsonian rat model: further biochemical and behavioral characterization

The main focus of the present study was to define the rotational response of 6-hydroxydopamine-lesioned rats to dopaminergic agonists to separate the partially lesioned rats from those having complete substantia nigra (SN) and ventral tegmental area (VTA) lesions. Animals were challenged by amphetamine and L-DOPA for 10 consecutive weeks. There was a correlation between rotational behavior and extent of midbrain cell loss. Rats with complete SN and < 40% VTA lesion turned more than 5 times/min after amphetamine administration, but not after L-DOPA; animals with complete SN and 40-80% VTA lesions turned vigorously following amphetamine and began turning after L-DOPA administration. Rats with complete SN and VTA lesions turned less after amphetamine than the other two groups, while their turning after L-DOPA administration increased. Extracellular dopamine (DA) measured by microdialysis, intracellular DA measured by postmortem tissue punches, and tyrosine hydroxylase-immunoreactive cell count in SN and VTA were also evaluated. It appears that the dopaminergic cells in the lateral VTA affect DA concentration in the medial caudate nucleus. In the nucleus accumbens of the lesioned side, DA release and metabolism substantially increased with the larger VTA lesion. Dopamine turnover rate in the caudate was also higher in the group with < 40% VTA lesion.

Fungal Elicitor-Induced Bean Proline-Rich Protein mRNA Down-Regulation Is Due to Destabilization That Is Transcription and Translation Dependent

In bean cells treated with fungal elicitor, the transcripts of PvPRP1, a gene encoding a proline-rich protein, decreased to ~6% of the original level within 4 hr. The apparent mRNA half-life during the period of rapid degradation was ~45 min. The rate of PvPRP1 gene transcription remained constant over this period, as determined by nuclear run-off assays, indicating a decrease in mRNA stability. By using actinomycin D to block transcription, the half-life of PvPRP1 mRNA in unelicited cells was estimated to be ~60 hr. In cells treated with actinomycin D followed by the addition of elicitor, the PvPRP1 mRNA half-life was ~18 hr, whereas cells treated with these reagents in reciprocal order exhibited a half-life of ~6 hr. The protein synthesis inhibitors emetine and anisomycin also inhibited the rate of PvPRP1 mRNA degradation in elicited cells. Based on these data, we concluded that the rapid decrease in the PvPRP1 mRNA level in elicited cells is due to destabilization, which is dependent on new RNA and protein synthesis.

The central effects of a nitric oxide synthase inhibitor (N omega-nitro-L-arginine) on blood pressure and plasma renin

An endothelium-derived relaxing factor has been identified as nitric oxide (NO). Peripheral and central administration of nitric oxide synthase inhibitors result in an increase in renal sympathetic nerve activity and an increase in blood pressure. The goal of our study was to determine if the increase in blood pressure following central NO synthase inhibition with N omega-nitro-L-arginine (L-NNA) is caused by the release of renin. Six groups of Sprague-Dawley rats were used. Group I (control) received intracerebroventricular (i.c.v.) artificial cerebrospinal fluid. Groups II & III received i.c.v. L-NNA, 5 & 15 micrograms/min. respectively. Group IV was treated with intravenous L-NNA, 15 micrograms/min. Group V, after bilateral nephrectomy, received i.c.v. L-NNA, 15 micrograms/min. Group VI received i.c.v. L-arginine, 60 micrograms/min. and i.c.v. L-NNA, 15 micrograms/min., simultaneously. Plasma renin concentration was measured in groups I, III, IV & V. Mean arterial blood pressure was significantly increased in groups II, III & V, i.e., following i.c.v. infusion of L-NNA. The increase in mean arterial blood pressure was significantly greater when the dose was increased from 5 to 15 micrograms/min. and it was eliminated when L-arginine was added to the infusion. The increase in blood pressure was attended by no change in heart rate. While the plasma renin concentration increased significantly in group III, this could not explain the increase in blood pressure since the nephrectomized group (V) showed no increase in renin concentration but an equivalent increase in blood pressure. The results show that acute central administration of a low dose of L-NNA increases blood pressure in rats and this increase can be prevented by central administration of L-arginine. However, intravenous infusion of the same dose (15 micrograms/min.) of L-NNA does not change blood pressure. We conclude that L-NNA acts directly within the central nervous system to increase blood pressure by a renin-independent mechanism. These results imply that central nitric oxide plays an important role in the regulation of blood pressure.

Induction of changes in the secondary structure of globular proteins by a hydrophobic surface

Circular dichroism, ellipsometry and radiolabeling techniques were employed to study the induction of changes in the secondary structure of BSA, myoglobin and cytochrome C by a hydrophobic surface. The results showed that adsorbed protein molecules lose their ordered native structure in the initial stage of adsorption and the structure appears to be a random or disordered conformation. Protein molecules adsorbed in later stages adopt a more ordered secondary structure (alpha helix and beta structure). The changes of secondary structure of globular proteins induced by a hydrophobic surface can be explained by the steric interaction between adsorbed proteins as well as by hydrophobic interactions during the adsorption process. In addition, there is obviously an intermediate stage in which the protein molecules are mainly in the beta structure, indicating that for certain proteins, the beta structure may be a more stable secondary structure than alpha helix on the hydrophobic surface.

Relative potency and efficacy of some dopamine agonists with varying selectivities for D1 and D2 receptors in MPTP-induced hemiparkinsonian monkeys

A series of dopamine agonists were studied on contraversive circling behavior in seven 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced hemiparkinsonian monkeys. The compounds selected included [1R,3S]3-(1' adamantyl)-1-aminomethyl-3,4-dihydro-5-6- dihydroxy-1H-2-benzopyran hydrochloride (A-77636), L-3,4-dihydroxyphenylalanine methyl ester hydrochloride ester (L-dopa-methyl ester), (-)-2-[N-propyl-N-(2-thienyl) ethyl-amino-5-hydroxy-tetralin]hydrochloride (N-0923), pergolide, (+)-(4aR)-trans-3,4,4a,5,6,10b-hexahydro-4-propyl-2H-n aphth[1,2-b]-1,2-oxazin-9-ol, naxagolide (PHNO), (+/-)6-chloro-7, 8-dihydroxy-2,3,4,5-tetrahydro-1-phenyl-1H-3-benzazepine hydrobromide, (+-) chloro-PB hydrobromide (SKF-81297) and (+-) 6-chloro-7,8-dihydroxy-3-allyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benza zep ine hydrobromide, (+-) chloro-APB hydrobromide (SKF-82958). The dose-effect relationship of each of these compounds was determined by measuring contraversive turns/120 min after an i.m. injection. There were marked differences in the potency and efficacy of the various compounds studied. The most potent compounds were the selective D2 agonists PHNO and N-0923. L-dopa methyl ester was equally effective, but much less potent. The D1 agonist A-77636 was equally effective. The D1 agonist SKF-82958 was also effective, but less potent. In the doses studied, the D1 agonist SKF-81297 was ineffective. With the exception of L-dopa methyl ester, the greater the D1/D2 affinity ratio, the greater the 50% of maximal dose to induce contraversive circling (r = 0.974, P < .05).

Developmental regulation and phytochrome-mediated induction of mRNAs encoding a proline-rich protein, glycine-rich proteins, and hydroxyproline-rich glycoproteins in Phaseolus vulgaris L

We have studied developmental and light regulation of mRNAs encoding a putative cell wall proline-rich protein (PvPRP1), cell wall glycine-rich proteins (GRPs), and cell wall hydroxyproline-rich glycoproteins (HRGPs) in bean (Phaseolus vulgaris). Light increases the levels of these mRNAs 2- to 150-fold in highly spatially regulated patterns during seedling development. These mRNA changes include differential regulation of transcripts derived from the GRP and HRGP multigene families. In 6-day-old light-grown seedlings, the PvPRP1 and GRP1.0 mRNAs were most abundant in the apical region of hypocotyls, epicotyls, and roots. In contrast, several HRGP transcripts were most abundant in the mature region of hypocotyls and roots in light-grown seedlings. When etiolated 6-day-old seedlings were illuminated with white light for 8 hr, maximal accumulation of PvPRP1 and GRP1.0 mRNAs occurred in the apical hook, whereas HRGP and GRP1.8 mRNAs accumulated in the mature region of hypocotyls. Etiolated seedlings subjected to a pulse of red light accumulated PvPRP1, GRP, and HRGP mRNAs in the hypocotyls. Far-red light inhibited red light induction of these mRNAs, indicating a phytochrome-mediated process. The possible roles of PRPs, GRPs, and HRGPs in cell differentiation and photomorphogenesis are discussed.

N-methyl-D-aspartate receptor antagonist and dopamine D1 and D2 agonist interactions in 1-methyl-4-phenyl-1,2,5,6-tetrahydropyridine-induced hemiparkinsonian monkeys

The noncompetitive N-methyl-D-aspartate antagonist (5R,10S)-(+)-5-methyl- 10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine hydrogen maleate (MK-801) and three dopamine agonists [(+/-)6-chloro-7,8-dihydroxy-2,3,4,5-tetrahydro-1-phenyl-1H-3-benzazepin e hydrobromide (SKF-81297), (+/-)6,chloro-7,8-dihydroxy-3-allyl-1-phenyl-2,3,4,5- tetrahydro-1H-3-benzazepine hydrobromide (SKF-82958) selective for D1 and (-)-2-[N-propyl-N-(2-thienyl)ethyl-amino-5- hydroxytetralin] hydrochloride (N-0923) selective for D2 receptors] were studied in seven adult female hemiparkinsonian Macaca nemestrina monkeys. Video recordings of free circling behavior showed that both SKF-82958 and N-0923 produced dose-related mean increases in contraversive rotations during the 120-min period after i.m. injection. SKF-81297 (21.1, 67.8 and 210.7 micrograms/kg) was relatively inactive compared to SKF-82958 (24.8, 74.8 and 234 micrograms/kg). The selective D2 agonist N-0923 (3.2, 10 and 32 micrograms/kg, i.m.) was the most potent in producing contraversive circling behavior. The noncompetitive N-methyl-D-aspartate antagonist dizocilpine (MK-801), in doses of 10 and 32 micrograms/kg i.m., produced a very slight increase in contraversive circling in contrast to the selective dopamine agonist SKF-82958. A large dose (100 micrograms/kg, i.m.) of MK-801 produced marked central nervous system depression. In combination with the dopamine agonists N-0923 and SKF-82958, MK-801 depressed contraversive circling in all doses studied. This study using hemiparkinsonian monkeys does not support the suggestion that a noncompetitive N-methyl-D-aspartate antagonist such as MK-801 would be useful in adjunctive therapy of human Parkinson's disease.

Selective amplification of cDNA sequence from total RNA by cassette-ligation mediated polymerase chain reaction (PCR): application to sequencing 6.5 kb genome segment of hantavirus strain B-1

A method, referred to as cassette-ligation mediated polymerase chain reaction (PCR), has been developed to permit selective and specific amplification of cDNA sequence from total cellular RNA. This technique comprises (i) digestion of cDNA with multiple restriction enzymes, (ii) ligation of cleavage products to double-stranded DNA cassettes possessing a corresponding restriction site and (iii) amplification of cassette-ligated restriction fragments containing a short, known sequence (but not all the other ligation products) by PCR using the specific and cassette primers; the specific primer is designed to prime synthesis from the known sequence of the cDNA whereas the cassette primer anneals to one strand of the cassette. Sequencing from the cassette primer provides information to design a new primer for the next walking step. The amplified cDNA fragments are often larger than the maximum DNA fragments (500-600 bp) that can be sequenced without the need of synthesizing internal sequencing primer. Each of such large cDNA fragments is dissected into smaller DNA fragments by repeating cassette-ligation mediated PCR exploiting different restriction sites and different sets of cassette primers. This dissection process reduces the number of specific primers to a minimum, thereby increasing the speed of sequencing and minimizing the overall cost. We have successfully applied this cDNA walking and sequencing by the cassette-ligation mediated PCR to the sequencing of an entire 6.5 kb genome segment of hantavirus strain B-1.(ABSTRACT TRUNCATED AT 250 WORDS)

[Determination of magnolol and honokiol in different processed samples of houpo by HPLC method]

HPLC was applied to determine and compare 17 samples of Houpo processed in different ways: sauted with ginger juice, dipped with ginger juice, boiled with ginger juice, and so on. The results provide a scientific basis for screening the best processing technology of Houpo.

[Nourishing yin action of the prepared rhizoma Rehmanniae]

The results of the experiment show that the prepared Rhizomae Rehmanniae can obviously improve the change of weight, quality of drinking water, urine and serum level of T3, T4 and AD of the hyperthyroid Yin deficient rats, and thus administers to the nourishing of Yin. The action of nourishing the kidney Yin is related with improving the serum level of AD in the body.

Negative and positive regulation of a novel proline-rich protein mRNA by fungal elicitor and wounding

The structure and expression of a cDNA clone (PvPRP1) isolated from a cDNA library prepared from bean (Phaseolus vulgaris) cells treated with fungal elicitor have been characterized. Sequence analysis of the 1.1 kb insert revealed a complete open reading frame which encodes a 32 kDa protein. The protein resembles other proline-rich proteins in plants but possesses several unique features: (i) the N-terminal half of the protein is proline rich and contains three identical repeats of Pro-Val-His-Pro-Pro-Val-Lys-Pro-Pro-Val and six related repeats; (ii) the proline-rich region contains two tracts of six histidine residues; and (iii) the C-terminal half is low in proline and lacks repeats. Genomic blotting experiments suggest the presence of a single PvPRP1 gene as well as more distantly related genes within the bean genome. A dramatic decrease in PvPRP1 mRNA levels occurs within 2 h of elicitor treatment of cell cultures. The PvPRP1 mRNA is present at a moderate level in hypocotyls. Upon wounding, the mRNA level initially decreases over 5 h and then accumulates over 25 h to levels which are higher than the basal level in unwounded hypocotyls. Based on the similarity to other proline-rich proteins with repeated motifs, including the presence of a putative signal peptide, it is likely that the PvPRP1 protein is targetted to the cell wall. The expression of the PvPRP1 gene appears to be integrated with the remodeling of the plant cell wall during the defense response.

[Effects of monoamine oxidase B inhibitor and MPTP (1-methyl-4-phenyl-1,2,3,6-tetra-hydropyridine) on enkephalin levels in mice]

The results of injecting 1-methyl-40 henyl-1,2,3,6-tetra-hydropyridine (MPTP) intraperitoneally to C57-BL black mice in doses of 36 mg/kg body weight each day for 7 days were analysed. Twelve days after the last MPTP injection, the levels of methionine-enkephalin (MEK) and leucine-enkephalin (LEK) in the mice striatum bodies were determined with radioimmunoassay. In the mice receiving MPTP, the average levels as compared with the controls were reduced by 75% for MEK (P less than 0.001) and by 66% for LEK (P less than 0.002). The levels of MEK and LEK in the mice receiving the monoamine oxidase inhibitor as well as MPTP did not differ significantly from the levels in the controls. The experimental data suggest that MPTP can affect the enkephalin system, while L-deprenyl can prevent MPTP-induced enkephalin depletion in the mice striatum bodies.