Structure of the maize mitochondrial replicon RNA b and its relationship with other autonomously replicating RNA species

The mitochondria of maize plants with S-type cytoplasm possess a family of single and double-stranded RNA molecules, termed RNA plasmids, that replicate in a DNA-independent manner typical of RNA viruses. We have determined the sequence of the smallest and most abundant member of this family, a single-stranded RNA termed RNA b. The 719 nucleotide sequence of RNA b lacks open reading frames of significant length. Probes complementary to the determined (+) strand sequence identified two larger RNA species of 2900 and > 4000 nucleotides in S-type maize mitochondria, the smaller of which corresponds to a previously identified member of the RNA plasmid family designated RNA a. These probes also unexpectedly identified a low abundance form of RNA b in N-type maize mitochondria. (+) strand probes identified corresponding (-) strand forms in S cytoplasm that likely represent components of replication intermediates. Primer extension experiments demonstrated that RNA b is an internally deleted form of the larger RNA plasmid, RNA a, and that it has a discrete and homogeneous 5' terminus. The solubility of RNA b in 2 M-LiCl as well as structural modelling studies indicated that it has a very high degree of secondary structure. Analysis of specific cleavage products generated by treatment of RNA b-oligonucleotide duplexes with RNase H indicated that the only identifiable forms of RNA b were linear molecules with relatively homogeneous 3' termini; no circular forms were detected. RNA b was found to share a 13 nucleotide sequence with the circular cadang-cadang viroid; 11 of these nucleotides fall within the central conserved region of viroid RNAs. In addition, RNA b shares certain structural similarities with phage Q beta and "variant" RNAs that serve as in vitro templates for the Q beta replicase. Collectively, our results indicate that RNA b is a "defective-interfering" member of an RNA family representing a new and apparently distinct class of RNA replicons.

Antigenic analysis of coxsackievirus B3 with monoclonal antibodies

All the 16 mouse monoclonal antibodies (McAbs) raised against Nancy strain of coxsackievirus B3, CoxB3(N), were type 3-specific. The reactivity of CoxB3(N) to this McAb panel during the serial passages showed a variation. Three field isolates of CoxB3, all neutralizable with the reference Anti-CoxB3 hyperimmune serum, were checked for the reactivities with the McAb panel. The isolates from the patients in Fujiang reacted with 12 McAbs and variably with the remaining four McAbs. On the basis of the reactivities with different virus strains, the McAbs were found to fall into four groups possibly corresponding to at least four epitopes. A considerable antigenic variation of CoxB3 was thus suggested.

[An experimental observation of effect of tetrandrine on pulmonary dysfunction in rabbit model of smoke inhalation injury]

A rabbit model with severe smoke inhalation injury was adopted to observe the effect of tetrandrine, a calcium antagonist, on pulmonary dysfunction after smoke inhalation during 24 hours post injury. It was found that tetrandrine could decrease the permeability of pulmonary and tracheal vascular permeability (p < 0.01), reduce lung edema and improve the function of respiration. These results imply that tetrandrine might be used in the treatment of inhalation injury.

Role of the gamma component of preprotoxin in expression of the yeast K1 killer phenotype

K1 killer strains of Saccharomyces cerevisiae secrete a polypeptide toxin to which they are themselves immune. The alpha and beta components of toxin comprise residues 45-147 and 234-316 of the 316-residue K1 preprotoxin. The intervening 86-residue segment is called gamma. A 26-residue signal peptide is removed on entry into the endoplasmic reticulum. The Kex2 protease excises the toxin components from the 290-residue glycosylated protoxin in a late Golgi compartment. Expression of a cDNA copy of the preprotoxin gene confers the complete K1 killer phenotype on sensitive cells. We now show that expression of immunity requires the alpha component and the N-terminal 31 residues of gamma. An additional C-terminal extension, either eight residues of gamma or three of four unrelated peptides, is also required. Expression of preprotoxin terminating at the alpha C-terminus, or lacking the gamma N-terminal half of gamma causes profound but reversible growth inhibition. Inhibition is suppressed in cis by the same 31 residues of gamma required for immunity to exocellular toxin in trans, but not by the presence of beta. Both immunity and growth inhibition are alleviated by insertions in alpha that inactivate toxin. Inhibition is not suppressed by kex2, chc1 or kre1 mutations, by growth at higher pH or temperature, or by normal K1 immunity. Inhibition, therefore, probably does not involve processing of the alpha toxin component at its N-terminus or release from the cell and binding to glucan receptors. Some insertion and substitution mutations in gamma severely reduce toxin secretion without affecting immunity. They are presumed to affect protoxin folding in the endoplasmic reticulum and translocation to the Golgi.

Somatostatin regulates excitatory amino acid receptor-mediated fast excitatory postsynaptic potential components in vagal motoneurons

Somatostatin is considered to be a brain neurotransmitter/neuromodulator; however, there is little concrete information on how this peptide contributes to generation of synaptic potentials in the mammalian central nervous tissue. Recently, a well-defined somatostatin-containing pathway has been traced from the subnucleus centralis of the solitarial complex to the compact formation of the nucleus ambiguus. Moreover, we have demonstrated both in vivo and in vitro that somatostatin enhances glutamate but inhibits acetylcholine excitation of ambigual motoneurons, suggesting involvement of this peptide in central oesophagomotor transmission. The availability of a brainstem slice containing this pathway has allowed us to characterize an excitatory amino acid receptor-mediated excitatory postsynaptic potential in compact formation neurons. This excitatory postsynaptic potential is unusual because its rising phase involves activation of N-methyl-D-aspartate receptors. Here we report that somatostatin participates in ambigual excitatory postsynaptic potential generation by permitting expression of the N-methyl-D-aspartate receptor-mediated component, thereby regulating fast information transfer in this pathway.

[Studies on a radioligand-receptor binding assay of human chorionic gonadotropin in rat testis]

A radioligand-receptor binding assay for human chorionic gonadotropin (HCG) has been established with cell membranes preparation of rat testis. Partially purified cell membranes preparation was prepared from rat testis by sucrose density gradient ultracentrifuge. The binding assay was performed by incubating 125I-HCG with rat testis cell membranes preparation at 30 degrees C for 1.5 h in a total incubation volume of 0.5 ml. Scatchard plot analysis for the binding assay revealed a linear binding plot and yielded a bound capacity of testis cell membranes receptors of 0.36 x 10(-12) mol/micrograms protein. KD of 0.45 x 10(-10) mol/L. Hill coefficient was 0.976. Studies on the kinetics of the reaction of radioligand-receptor binding showed that the mean values for the association rate (k1) and dissociation constants (k2) were individually 0.41 x 10(-3) pmol/min and 2.12 x 10(-3) pmol/min; the dissociation plot was two-phase, with 15 x 10(-3) pmol/min of fast-phase and 1.5 x 10(-3) pmol/min of slow-phase.

Kinetic analysis of the 5' splice junction hydrolysis of a group II intron promoted by domain 5

The 5' splice junction (5'SJ) of Group II intron transcripts is subject to a specific hydrolysis reaction (SJH). This reaction occurs either within a single transcript containing intron sequences through domain 5 (D5) or by cooperation of two separate transcripts, one bearing the 5'SJ and another contributing D5 (1). In this report we describe the latter reaction in terms of its kinetic parameters. A minimal D5 RNA of 36 nts (GGD5) was sufficient to promote SJH of a second transcript containing the 5' exon plus intron domains 1, 2, and 3 (E1:123). Equimolar production of two RNAs, the 5' exon (E1) and an intron fragment containing domains 1, 2, and 3 (123) was observed. The kinetic coefficients were evaluated by an excess GGD5 approach. The apparent Km was complex, varying with GGD5 concentration. This behavior indicates heterogeneity in E1:123 with respect to GGD5 binding. The binding heterogeneity may result from formation of E1:123 dimers or from nicks in some molecules of each E1:123 preparation. The heterogeneity was always evident, but to a variable degree, regardless of the procedure by which E1:123 was isolated. The system may be described in terms of parameters analogous to kcat and Km. At infinite dilution of GGD5, the characterizing values were: k2 degrees (the analog of kcat) = 0.0055 min-1 and Km degrees = 0.22 microM. In the limit of GGD5 saturation, the values were: k2 infinity = 0.012 min-1 and Km infinity = 4.5 microM. A natural variant D5, representing the sequence from intron 1 of the yeast cytochrome-b gene, was also functional in SJH. This GGD5b1 was governed by similar Km degrees and Km infinity values, but was only one-third as active over the entire D5 concentration range. A different D5 isomer was entirely ineffective for SJH.

Immunocytochemical localization and endogenous synthesis of apolipoprotein E in testicular Leydig cells

Apolipoprotein E (apoE) is synthesized by a wide variety of tissues, including those involved in steroidogenesis; its function in most extrahepatic tissues is unknown. Significant amounts of apoE mRNA have been detected in the testis, but the cellular origin of this material has not yet been determined. The purpose of the present study was to determine whether the steroidogenic cells of the testis synthesize apoE. We localized apoE in the testis of mice by an avidin-biotin peroxidase technique using a cross-reactive anti-rat apoE antibody. ApoE immunoreactivity was strongest in interstitial cells but was also diffusely localized throughout the seminiferous tubules. Acute treatment of mice with hCG diminished apoE immunoreactivity in the testis. A murine Leydig tumor cell line (I-10 cells) also demonstrated apoE immunoreactivity, suggesting that at least one source of interstitial apoE is the Leydig cell. Normal Leydig cells were subsequently isolated from control and hCG-treated mice using Percoll density gradients. Isolated hepatocytes, I-10 cells, and Leydig cells (with or without hCG in vitro) were incubated in the presence of [35S]methionine. A 35S-labeled protein of approximately 33-35 kDa was immunoprecipitated from the cells and media of all three types of preparations using whole antiserum or affinity-purified antibody. Preincubating the antibodies with apoE-containing murine very low-density lipoprotein or purified rat apoE eliminated these bands. Leydig cell apoE synthesis and secretion were decreased by hCG treatment in vivo and/or in vitro. These data suggest that apoE is synthesized by normal and transformed Leydig cells and may play a role in sterol transport in the testis.

Functional status, education, and the diagnosis of dementia in the Shanghai survey

We examined the relationship of culturally adapted Chinese versions of the Mini-Mental State Examination (CMMS) and several functional measures to the effect of education on the clinical diagnosis of dementia in 554 subjects (55 to 95 years; median, 74) who had undergone intensive evaluation during the Shanghai survey of dementia. Low education was associated with increased prevalence of clinically diagnosed dementia. The standardized history and one functional scale (Pfeffer Outpatient Disability Scale [POD]) clustered closely with clinical diagnosis on factor analysis, whereas the CMMS, Instrumental Activities of Daily Living scale (IADL), and Activities of Daily Living scale (ADL) loaded additionally onto an education-weighted component. A logistic equation based on the CMMS, history, POD, and IADL was the best predictor of the clinical diagnosis of dementia, but history, POD, and IADL without a mental status score also predicted the diagnosis with a sensitivity of 88.6%, a specificity of 89.3%, a positive predictive value of 66.0%, and a negative predictive value of 97.1%. When dementia was diagnosed using an algorithm based on the three functional scales alone, low education continued to be associated with increased age-specific risk of dementia.

Combination of DNA single strand synthesis with PCR to construct mung bean trypsin inhibitor gene

This paper using the synthesis of mung bean trypsin inhibitor gene as an example, presented a new method for gene synthesis. The principle of the method was based on the combination of the single strand strategy and the PCR technique. The synthesis was very simple, convenient and rapid. The mung bean trypsin inhibitor is a protein composed of 72 amino acid residues. Its amino acid sequence has been determined, but the DNA sequence of gene still unknown. The synthetic mung bean trypsin inhibitor gene was 248 bp in length. It contains the encoded sequence, the start and stop codons, the restriction sites of EcoRI and BamHI at both ends, The codon selection of the synthetic gene was carried out according to the codon usage of other plant protease inhibitor gene or plant gene. The synthetic double-stranded DNA was digested with EcoRI and BamHI or PstI first, then cloned into plasmid pUC19. The synthetic gene was proved to be correct by the restriction map and the sequence analysis using the dideoxy-mediated chain termination method.

Intensity just-noticeable differences at equal-loudness levels in normal and pathological ears

The relationship between loudness level and intensity discrimination was investigated in the frequency range 0.5-6.5 kHz by comparing the intensity just-noticeable differences (jnd's) at a number of equal-loudness levels in the better and poorer ears of eight individuals with essentially unilateral hearing loss of cochlear origin. Such hearing loss usually produces loudness recruitment, altering the relationships among the loudness, sound-pressure level (SPL), and sensation-level (SL) variables, so that their effects can be separated. In these experiments, the jnd's were correlated with loudness level, not SPL or SL. Although, in some listeners, there were significant differences between jnd's in the two ears at some binaurally equal-loudness levels, they were not systematic over the group of listeners. Statistically, there was no significant difference between equal-loudness jnd's in the two ears, whereas the corresponding SLs and SPLs were significantly different. The rate of loudness growth had no effect on the jnd's. As expected from the near-miss to Weber's law, the mean jnd's decreased with sound intensity. The corresponding decrease in the mean Weber fraction, delta I/I, was accompanied by a decrement in its intrasubject standard deviation. The latter was correlated with the mean, independent of its relationship to SPL or SL.

O2A progenitor cells transplanted into the neonatal rat brain develop into oligodendrocytes but not astrocytes

The differentiation of the bipotential O2A progenitor cell into an oligodendrocyte or a type 2 astrocyte has been well documented in cell cultures of various regions of the central nervous system. The appropriate tools to prove its existence in vivo have been lacking. We report on an in vitro-in vivo approach that combines stable labeling of an enriched population of cultured O2A progenitors by the fluorescent dye fast blue, followed by their transplantation into neonatal rat brains, which allowed us to study the influence of the brain microenvironment on their lineage decision. The grafted cells survived well and 21 days after grafting nearly all were positive for the oligodendroglial marker galactocerebroside. Surprisingly, the fast blue-positive grafted cells did not stain for the astroglial marker glial fibrillary acidic protein. These results indicate that the O2A progenitor's plasticity is restricted by the in vivo environment, resulting in the developmental exclusion of the type 2 astrocyte initially described in vitro.

Simultaneous measurement of left atrial pressure by Doppler echocardiography and catheterization

Simultaneous, continuous wave Doppler echocardiography, left ventricular systolic and mean pulmonary capillary wedge pressure measurements were performed during cardiac catheterization in 54 patients with mitral regurgitation. Doppler-derived left atrial pressure, which was calculated by subtracting mitral regurgitant gradient from brachial artery systolic pressure, correlated well with mean pulmonary capillary wedge pressure by catheter (r = 0.933, SEE = 2.9 mmHg, P < 0.001); a comparison between non-invasive and invasive systolic gradients across the mitral valve yielded a high correlation (r = 0.91, SEE = 6.0 mmHg, P < 0.001); and there was also a high correlation between brachial artery and left ventricular systolic pressures (r = 0.93, SEE = 4.9 mmHg, P < 0.01). It is concluded that Doppler echocardiography provides a reliable and accurate method for complete non-invasive assessment of left atrial pressure in patients with mitral regurgitation.

Cloning and intracellular localization of the U2 small nuclear ribonucleoprotein auxiliary factor small subunit

U2 small nuclear ribonucleoprotein auxiliary factor (U2AF), an essential mammalian splicing factor, is composed of two subunits: a 65-kDa protein (U2AF65), which binds the pre-mRNA polypyrimidine tract and is required for in vitro splicing, and an associated 35-kDa protein (U2AF35). Here we report the isolation of a cDNA encoding U2AF35. U2AF35 contains sequence motifs found in several mammalian pre-mRNA splicing factors. We show directly that U2AF65 and U2AF35 interact with each other and delineate the regions of both proteins that mediate this interaction. Using anti-peptide antibodies against U2AF35, we show that the protein has the intracellular distribution characteristic of U2AF65. Both U2AF65 and U2AF35 are concentrated in a small number of nuclear foci corresponding to coiled bodies, subnuclear organelles first identified by light microscopy in 1903.

Energetic Charged-Particle Phenomena in the Jovian Magnetosphere: First Results from the Ulysses COSPIN Collaboration

The Ulysses spacecraft made the first exploration of the region of Jupiter's magnetosphere at high Jovigraphic latitudes ( approximately 37 degrees south) on the dusk side and reached higher magnetic latitudes ( approximately 49 degrees north) on the day side than any previous mission to Jupiter. The cosmic and solar particle investigations (COSPIN) instrumentation achieved a remarkably well integrated set of observations of energetic charged particles in the energy ranges of approximately 1 to 170 megaelectron volts for electrons and 0.3 to 20 megaelectron volts for protons and heavier nuclei. The new findings include (i) an apparent polar cap region in the northern hemisphere in which energetic charged particles following Jovian magnetic field lines may have direct access to the interplanetary medium, (ii) high-energy electron bursts (rise times </= 1 minute and energies extending to > approximately 17 megaelectron volts) on the dusk side that are apparently associated with field-aligned currents and radio burst emissions, (iii) persistence of the global 10-hour relativistic electron "clock" phenomenon throughout Jupiter's magnetosphere, (iv) on the basis of charged-particle measurements, apparent dragging of magnetic field lines at large radii in the dusk sector toward the tail, and (v) consistent outflow of megaelectron volt electrons and large-scale departures from corotation for nucleons.

[Doppler echocardiography for measuring the right ventricular diastolic function]

To noninvasively measure the right ventricular diastolic function, continuous wave Doppler echocardiography was used in 31 patients with tricuspid regurgitation (TR). The right ventricular pressure (RVP) curves were analyzed mathematically, showing that RVP declined exponentially after maximum-dP/dt. The instantaneous RVPs during isovolumetric relaxation were measured from RVP curves and also calculated by using exponential equations. There were high correlations between measured and calculated RVPs (r = 0.83-0.98). The tricuspid regurgitant velocities were recorded by CWD and converted into pressure gradients (PG) using a simplified Bornoulli equation. The instantaneous RVPs were then obtained by adding an assumed right atrial pressure to PGs. The maximum-dP/dt, the instantaneous RVP at the time of -dP/dt max (PO) and the time constant of right ventricular relaxation (T) were calculated from both RVP curves and Doppler spectra. The results showed that there were high correlations of -dP/dt max, PO and T measured by two techniques (r = 0.95, 0.98 and 0.92). We conclude that T can be used to quantitate right ventricular myocardial relaxation, and CWD offers a new technique for noninvasively measuring T in patients with TR.

Interim report of Sino-Monica-Beijing for the years 1985-1989

Interim results of Sino-Monica-Beijing for the 5 year period 1985-1989 are reported. The cardiovascular disease (CVD) risk factors increased between the surveys carried out in 1984-1985 and 1988-1989, especially blood cholesterol and body mass index.

[The use of 6-flavor Rehmannia decoction with additives in the prevention of ototoxic deafness induced by gentamicin in guinea pigs]

The purpose of this study is to discuss the effects of the Chinese medicine six-flavor Rehmannia Decoction with additives on preventing deafness induced by gentamicin (GM) in guinea pig by means of testing the thresholds of Preyer's reflex (PR) cochlear microphonic potential (CM), action potential of the auditory nerve (N1) and scanning electron microscope of inner ear (SEM). The results showed that the medicine is effective in reducing the ototoxic effect of GM on inner ear.

Protection effects of procaine on oxidative stress and toxicities of renal cortical slices from rats caused by cisplatin in vitro

Incubation of rat renal cortical slices with 2 mM cisplatin (CDDP) at 37 degrees C for different periods of time (15-180 min) increased malondialdehyde (MDA) formation, decreased intracellular glutathione (GSH), and inhibited gluconeogenesis in the slices. CDDP-induced MDA formation increased by 53% after 180 min of incubation and GSH decreased by 35% after 60 min of incubation. Both depletion of GSH and inhibition of gluconeogenesis preceded MDA formation. Procaine (2 mM) completely inhibited CDDP-induced lipid peroxidation without affecting depletion of GSH, but even potentiated gluconeogenesis inhibition, while 2 mM dithiothreitol (DTT) largely reversed all of these biochemical indices. After 240 min of incubation, 2 mM CDDP produced marked cytotoxicities, characterized by an increase in leakage of alkaline phosphatase (ALP) (132%), lactate dehydrogenase (LDH) (115%) and N-acetyl-beta-glucosaminidase (NAG) (157%), decrease in intracellular K+ (64%), and change in total water contents in the slices. Procaine (2 mM) showed protection against CDDP-induced cytotoxicities to a certain extent. These results suggest that depletion of GSH might be a determinant step in the oxidative stress and subsequent cytotoxicity, and that procaine is a powerful antioxidant and would be a promising drug for ameliorating some of the adverse effects of CDDP.

Gene frequencies of alcohol dehydrogenase2 and aldehyde dehydrogenase2 in Northwest Coast Amerindians

The frequencies of the alleles encoding isozymes of alcohol dehydrogenase and aldehyde dehydrogenase were low in Northwest Coast Amerindians compared to Chinese subjects.

A study of the stability of W/O/W multiple emulsions

The stability of W/O/W emulsions has been studied in batch agitators. The surfactants suitable for W/O/W emulsions were screened and the factors affecting the emulsion stability were also studied. Results showed that polyamine E644 was an excellent emulsifier for W/O emulsions since the emulsion stabilized by it has not only good stability but also shows smaller swelling. The stability of the emulsion increases with increase in membrane viscosity and concentration of surfactant, but decreases with increase in concentration of the internal reagent in the internal phase and the carriers in the membrane. Raising the agitation speed and the time for preparing the W/O emulsion is beneficial to membrane stability due to formation of smaller internal droplets, but raising the speed for dispersing the W/O emulsion in the external phase results in an increase in membrane breakage.

[Pharmacological study on spleen-stomach warming and analgesic actions of Aconitum carmichaeli Debx]

This study presents an observation of the anti-inflammatory effect of Aconitum carmichaeli decoction on water-immersion stress induced gastric ulcer in mice and 0.6 mol/L HCl induced gastric ulcer in rats. The observation showed that the decoction was resistant to the castor oil induced and Cassia angustifolia leaf induced experimental diarrhea in mice, and also had marked analgesic action. It is thus suggested that Aconitum carmichaeli is useful clinically as a spleen-stomach warming and analgesic agent in traditional Chinese medicine.