Targeted cleavage of mRNA by human RNase P

Ribonuclease P from Escherichia coli can cleave RNAs in simple, hydrogen-bonded complexes of two oligoribonucleotides that resemble the aminoacyl stem and 5' leader sequence of tRNA precursors. RNase P from human (HeLa) cells cannot catalyze the cleavage in vitro of the 5'-proximal oligoribonucleotide that contains the leader sequence in such simple complexes but can do so when the 3'-proximal oligoribonucleotide (external guide sequence) is altered to resemble three-quarters of a tRNA molecule. In such a complex, the efficiency of cleavage of the mRNA for chloramphenicol acetyltransferase, as the 5'-proximal oligoribonucleotide, depends on the structural details of the external guide sequence and on the choice of target site within the mRNA. The presence of the appropriately designed external guide sequence in cells in tissue culture reduces chloramphenicol acetyltransferase activity and the level of the corresponding intact mRNA in the cells. Thus, it appears that the use of such external guide sequences may provide a general technique for gene inactivation.

[Pulmonary function disturbances in patients with hepatic cirrhosis]

The results of five pulmonary function tests on 52 patients with uncompensated hepatic cirrhosis were presented. Compared with matched healthy adults, the patients had decreased values of VC, TLC and DLCO, and their RV/TLC increased (P < 0.05-0.001). Possible pathogenic factors were investigated. The ascites showed evident influences on pulmonary function. In addition to the disorders detected by the above 4 tests, FRC decreased in the patients with ascites. A comparison between the patients with albumin below 30g/L and the patients with albumin above 30g/L revealed that reduced plasma albumin also played role in decreasing VC, TLC and DLCO. Besides the effects of ascites, severe varices of esophagus should have relation to the increase of RV/TLC and the decrease of DLCO.

Flow modulates coronary venular permeability by a nitric oxide-related mechanism

This study demonstrates that flow velocity modulates coronary venular permeability to albumin. Apparent permeability coefficients of albumin (Pa) were measured in isolated cannulated coronary venules ranging from 30 to 70 microns in diameter. Hydrostatic and oncotic pressures were controlled while the intraluminal flow velocity was varied. Pa at an intraluminal hydrostatic pressure of 12 cmH2O and a flow velocity of 7 mm/s was 4.01 +/- 0.53 x 10(-6) cm/s. Increasing flow velocity to 10 and 13 mm/s augmented the permeability by 33 +/- 14 and 48 +/- 14%, respectively. The nitric oxide synthase inhibitor, NG-monomethyl-L-arginine (L-NMMA) (10(-5) M), decreased baseline Pa and abolished the flow-induced permeability changes. Administration of L-arginine (3 x 10(-3) M), a physiological precursor of nitric oxide which reverses the effect of L-NMMA, restored the relationship between flow and permeability. From these results we conclude that 1) flow velocity should be considered as a physical force that potentially modulates permeability of venular exchange vessels in the heart and 2) flow modulates coronary venular permeability via the production of nitric oxide.

[Studies of Rehmannia glutinosa Libosch. f. hueichingensis as a blood tonic]

We have studied the function of dried and prepared Rehmannia glutinosa f. hueichingensis in treating hemorrhagic anemic mice and in fostering bone marrow hematopoietic cells CFU-S, CFU-E. The results show that Rehmannia glutinosa f. hueichingensis can promote the recovery of blood deficient animals, RBC. Hb expedite the multiplication and differentiation of CFU-S, CFU-E, and thus proves markedly helpful to the generation of blood.

Monoclonal antibodies define genus-specific, species-specific, and cross-reactive epitopes of the chlamydial 60-kilodalton heat shock protein (hsp60): specific immunodetection and purification of chlamydial hsp60

Ocular and urogenital tract infections with Chlamydia trachomatis can progress to chronic inflammatory diseases that produce blindness and tubal infertility. The pathophysiology of these chronic disease conditions is thought to be immunologically mediated, and the chlamydial 60-kDa heat shock protein (hsp60) has been implicated as a major target antigen that stimulates the immunopathological response. The lack of chlamydial hsp60 antibodies and purified hsp60 has severely restricted studies to define more thoroughly the role of this protein in the immunopathogenesis of chlamydial disease. We produced a panel of antichlamydial hsp60 monoclonal antibodies (MAbs) and defined their specificities by immunoblotting against lysates of C. trachomatis, C. psittaci, and six other genera of bacteria. Three patterns of anti-hsp60 immunoreactivity were observed: chlamydial species specific, chlamydial genus specific, and cross-reactive. The epitopes recognized by these MAbs were localized within the primary amino acid sequence of hsp60 by immunoblotting against recombinant amino-terminal truncated hsp60 fusion polypeptides and then precisely mapped by use of overlapping synthetic peptides. The majority of the MAbs mapped to either the amino or the carboxyl termini of hsp60. Epitopes defining all three MAb reactivities mapped within amino-terminal residues 6 to 16. Genus-specific hsp60 MAbs mapped to epitopes located within this region and to residues 17 to 28 and 177 to 189. Antichlamydial hsp60 MAbs stained inclusions as effectively as MAbs specific for the major outer membrane protein. Homogeneous preparations of full-length recombinant chlamydial hsp60 and amino-terminal truncated recombinant hsp60 polypeptides were obtained by immunoabsorption chromatography with an hsp60 MAb reactive to the carboxyl terminus of the protein. Thus, the antichlamydial MAbs described here should be extremely useful for the specific immunodetection of hsp60 in tissues from individuals having different disease manifestations and for the purification of hsp60 or truncated hsp60 polypeptides for use in serologic and lymphocyte proliferation assays. The availability of these MAbs will facilitate studies to define more precisely the role of hsp60 in the immunopathogenesis of chlamydial disease.

[Analysis of chemical constituent of essential oil in Lonicera japonnica Thunb. cultivated on the northern plain of Henan Province]

The chemical constituents of the essential oil in the dry flower and fresh flower of Lonicera japonica were analyzed by the GC-MS-DS technique and the superimposition of authentic samples. 27 and 30 monoterpenoids and sesquiterpenoids were identified from the essential oil of the dry flower and fresh flower respectively. The major constituents have been found to be linalool, geraniol, aromadendrene and eugenol etc.

Real-time parallel optical logic operation using photorefractive two-wave mixing and fringe-shifting techniques

The coupling effect between phase and intensity in photorefractive two-wave mixing in a Bi(12)SiO(20) crystal is demonstrated. By using interference fringe-shifting techniques that are executed by a Mach-Zehnder interferometer, an optical parallel logic operation system that is based on the coupling effect is implemented.

Investigation of a new wide-band transducer with piezoelectric layered ring

A type of transmitting transducer with a piezoelectric layered ring is described. It is wide band, applicable to low-frequency operation, and has horizontal nondirectivity. Theoretical analysis and structural design are both discussed. Experimental results show: (1) the flat and smooth transmitting frequency response of the experimental transducer ranges from 9 to 20 kHz with the fluctuation not exceeding +/-1 dB; (2) within this wide band the electroacoustic efficiency reaches 30%-60%; and (3) when a small signal is used as excitation, the theoretical frequency response curve coincides very well with the experimental curve.

Effect of low- and high-frequency TENS on Met-enkephalin-Arg-Phe and dynorphin A immunoreactivity in human lumbar CSF

Transcutaneous nerve stimulation (TENS) treatment was given for 30 min to 37 patients divided into 3 groups of 10 patients and 1 group of 7 patients. Two groups received low-frequency (2 Hz) and the other 2 groups high-frequency (100 Hz) stimulation. A diagnostic lumbar cerebrospinal fluid (CSF) sample was obtained immediately before and after stimulation. The CSF samples were subjected to analysis of immunoreactive (ir) opioid peptides, Met-enkephalin-Arg-Phe (MEAP) from preproenkephalin and dynorphin A (Dyn A) from preprodynorphin, respectively. Low frequency TENS applied on the hand and the leg resulted in a marked increase (367%, P less than 0.05) of ir-MEAP but not ir-Dyn A, whereas high-frequency (100 Hz) TENS produced a 49% increase in ir-Dyn A (P less than 0.01) but not ir-MEAP. This is the first report in humans that 2 Hz and 100 Hz peripheral stimulation induces differential release of peptides from preproenkephalin and preprodynorphin, respectively.

The 40-kilodalton to autoantigen associates with nucleotides 21 to 64 of human mitochondrial RNA processing/7-2 RNA in vitro

A 40-kDa To antigen recognized by sera from some patients with autoimmune diseases is an integral component of both human RNase P and mitochondrial RNA processing (MRP) RNase. Human MRP and RNase P RNAs, synthesized in vitro, readily associate with the To antigen present in the HeLa cell extract. Using this in vitro reconstitution system, the binding site of the To antigen is localized to a 44-nucleotide-long sequence corresponding to nucleotides 21 to 64 of the human MRP RNA. UV cross-linking experiments showed that the To antigen binds directly to MRP RNA and to RNase P (H1) RNA through RNA-protein interactions. Although the MRP RNA and RNAse P (H1) RNA show sequence homology in four conserved blocks (H. A. Gold, J. N. Topper, D. A. Clayton, and J. Craft, Science 245:1377-1380, 1989), the To antigen-binding site in MRP RNA does not show any obvious primary sequence homology with H1 RNA. These data suggest that the To antigen binds to a conserved and presumably a common secondary or tertiary structure in human MRP and RNase P RNAs.

5' flanking sequences of human MRP/7-2 RNA gene are required and sufficient for the transcription by RNA polymerase III

Human mitochondrial RNA processing (MRP) RNA is a 270 nucleotide-long small RNA found as ribonucleoprotein particles. In this study, we isolated four human genomic clones with homology to human MRP RNA. Two of these clones contained one copy each of the real gene coding for human MRP RNA; the other two clones represented a processed psuedogene. The Southern blot with the genomic DNA showed that the haploid human genome contains one copy of real gene and a few pseudogenes for MRP/7-2 RNA. The human MRP RNA is synthesized by RNA polymerase III and the 5' flanking sequences -84 to 1 of MRP RNA gene, containing TATA and PSE-like elements, are required and sufficient for transcription in vitro.

A method for isolation and fluorescent labeling of rat neutrophils for intravital microvascular studies

A method for the isolation, fluorescent labeling, and reinfusion of rat neutrophils for in vivo investigation of white blood cell function in the microcirculation is described. The cell surface morphology and function of the labeled and unlabeled neutrophils were compared in vitro and in vivo. The morphology of the labeled and unlabeled cells was visually assessed by differential interference contrast microscopy before and after exposure to the chemotactic peptide FMLP. Labeled and unlabeled cells were morphologically similar under normal and stimulated conditions. The chemotactic responsiveness of the labeled and unlabeled cells was evaluated in vitro by quantifying the movement of cells across a porous membrane in response to FMLP. No significant difference in chemotactic responsiveness was found. The in vivo behavior of the labeled neutrophils was quantitatively studied by examining their interactions with the venular endothelium in the rat cremaster muscle. Rolling velocity for labeled neutrophils and unlabeled white blood cells was measured at different flow velocities and wall shear rates. No difference was found between the labeled and unlabeled cells. It is concluded that this isolation and labeling procedure yields cells possessing normal morphology and function. These labeled neutrophils may be useful for in vivo study of their behavior in the microcirculation.

Multiple tandem promoters of the major outer membrane protein gene (omp1) of Chlamydia psittaci

The transcription of omp1, the gene encoding the major outer membrane protein, was studied for two strains of Chlamydia psittaci, guinea pig inclusion conjunctivitis (GPIC) and mouse pneumonitis (Mn). The transcriptional initiation sites for the omp1 of each strain were mapped by S1 nuclease and primer extension analyses. Three different sizes of omp1 transcripts were observed for GPIC and four were observed for Mn. The production of these transcripts appeared to be the consequence of multiple tandem promoters. The order in which the omp1 RNA transcripts appeared during the growth cycle of the C. psittaci strains was found to differ from that of C. trachomatis.

Performance of real time associative memory using a photorefractive crystal and liquid crystal electrooptic switches

We present a real time holographic associative memory implemented with photorefractive KNSBN:Co crystal as the memory element and a liquid crystal electrooptic switch array as the reflective thresholding device. Our experiment stores and recalls two images and shows that the system has real time multiple-image storage and recall functions. An associative memory with a dynamic threshold level to decide the closest match of an incomplete input is proposed.

The Chlamydia trachomatis hyp operon is homologous to the groE stress response operon of Escherichia coli

The Chlamydia trachomatis serovar A hyp operon was cloned, sequenced, and expressed in Escherichia coli. Two cotranscribed open reading frames, hypA and hypB, encoded polypeptides of 17 and 57 kilodaltons, respectively. The deduced amino acid sequences of serovar A HypA and HypB proteins were (respectively) 85 and 94% identical with HypA and HypB proteins of Chlamydia psittaci GPIC, and HypB was greater than 50% identical to 60-kilodalton stress response proteins from other procaryotes and eucaryotes. The sequence should be useful in defining the antigenic structure of the Chlamydia trachomatis HypB protein, a necessary step toward understanding the relationship between the immune response to this protein and the pathogenesis of human chlamydial diseases.

[Argon replacing helium in measurement of pulmonary carbon monoxide diffusing capacity, its normal value and clinical application]

Measuring DL COSB of 120 normal subjects by using a gas mixture, in which helium was replaced by argon, we determined the DL COSB mean value, standard deviation and the predicted value formula for both sexes. The lower limit value of DL COSB for normal subjects was defined and the positive diagnostic value investigated. A ratio of actual value to predicted value below 80% was defined as abnormal. With this diagnostic criterion 43 cases of silicosis and diffuse pulmonary interstitial fibrosis were investigated, the positive rate of the cases being 90.70%, with a false positive rate of below 10% for normal subjects, which indicates that this gas mixture and the criterion are applicable for clinical practice.

[A classification study of ovarian mucinous cystadenoma using fuzzy mathematics]

Ovarian mucinous cystadenomas (OMCA) are classified into three groups: benign, borderline and malignant. During diagnosis, pathologists often feel puzzled. Quantitative or semiquantitative computer-aided diagnosis is also defective. By using fuzzy mathematics, 129 cases (134 tumors) were studied. At first, they were classified objectively by fuzzy cluster analysis, and the results were used as the basis of study and the judicial criteria of methods. Using these data, an equation of fuzzy synthetical judgement was established. Then these cases were diagnosed again by the equation. The conforming rate was 96.27% (129/134). For comparison, from these data pluralistic concept regression equation was acquired by the computer, then these cases were diagnosed again by the equation, and the conforming rate was 94.03% (126/134). The difficulties in classification of OMCA are analysed and their causes are discussed. Compared with other methods, the merits and demerits of this new method are emphasized.

Secondary structure of 7SK and 7-2 small RNAs. Possible origin of some 7SK pseudogenes from cDNA formed through self-priming by 7SK RNA

Pseudogenes having homology to small RNAs, like 7SL, 7SK, 6S, 4.5S, U1, U2, and U3 RNAs, are abundant and dispersed in the genomes of higher eukaryotes [reviewed in Weiner et al. (1986) Annu. Rev. Biochem. 55, 631-661]. To understand better the possible origin of these pseudogenes, we studied the abilities of cytoplasmic 7SL, 7SK, and nucleolar 7-2 RNAs to self-prime and result in the synthesis of cDNAs. When rat 7SK RNA was used as substrate, a 294-nucleotide-long cDNA was synthesized in vitro by reverse transcriptase, indicating that the 3' end of 7SK RNA can act in a self-priming manner to generate 7SK cDNA. When 7-2 RNA was used as a substrate, a cDNA of approximately 235 nucleotides was observed; 7SL RNA did not act as a self-primer. Earlier studies have shown that DNAs homologous to 7SK RNA are represented by a moderately reiterated family in the mammalian genomes and many of these sequences were found to be truncated 7SK pseudogenes [Murphy et al. (1984) J. Mol. Biol. 177, 575-590]. In this study, one 7SK clone from the rat genome was characterized by sequencing. This clone contained 243 base pairs homologous to the 5' end of 7SK RNA, and was flanked by direct repeats. These data suggest that, as previously proposed for some U3 pseudogenes [Bernstein et al. (1983) Cell 32, 461-472], one mechanism for the generation of truncated 7SK pseudogenes may be the integration of self-primed reverse transcripts of 7SK RNA at random genomic sites.

Students performance vs. hospital performance in the labor market for medical interns and residents. Do hospitals perform better due to asymmetry in information available to them relative to students?

This paper concerns the labor market for medical interns and residents in the U.S., and in particular, the question of whether the current matching mechanism between graduating medical students and hospitals is 'informationally inefficient'. It was found that overall students performed better than hospital programs in contrast to the common claim that hospitals are more likely to perform better due to seeming superiority in analyzing publicly available information or through access to non-publicly available information. We also conducted a similar analysis for the different specialty programs. In six specialty programs the students' performance was better than hospitals, in two specialty programs the hospitals performance was better than the students and in 14 specialty programs the difference in performance was not statistically different from zero. Thus, only in two cases the hypothesis that the specialty market is informationally inefficient cannot be rejected using the data available. It should be noted that this market is atypical (compared with other labor markets) in that we can test whether it is informationally inefficient by using a practical definition adopted from the field of finance.

Rat nucleolar 7-2 RNA is homologous to mouse mitochondrial RNase mitochondrial RNA-processing RNA

7-2 RNA (also termed RNA M and 7SM RNA) is a noncapped small RNA present in small ribonucleoprotein particles; these particles are present in the granular compartment of the nucleolus. Some sera from patients with scleroderma specifically immunoprecipitate 7-2 RNA-containing particles (Hashimoto, C., and Steitz, J. A. (1983) J. Biol. Chem. 258, 1379-1382; Reddy, R., Tan, E. M., Henning, D., Nohga, K., and Busch, H. (1983) J. Biol. Chem. 258, 1383-1386; Reimer, G., Raska, I., Scheer, U., and Tan, E.M. (1988) Exp. Cell Res. 176, 117-128). In this study, the primary sequence of Novikoff hepatoma 7-2 RNA was determined and a possible secondary structure is presented. The Novikoff hepatoma 7-2 RNA is 94% homologous to the recently described mouse mitochondrial RNase MRP RNA, suggesting that Novikoff hepatoma 7-2 RNA may be the homologue of mouse MRP RNA. The presence of 7-2 RNA in nucleoli and in mitochondria suggests that 7-2 ribonucleoproteins, in addition to being essential components of mitochondrial RNase, may also be functional in nucleolar RNA processing and ribosome biogenesis.

Genes for human U3 small nucleolar RNA contain highly conserved flanking sequences

Six human genomic clones containing sequences homologous to the U3 small nuclear RNA (snRNA) were isolated and characterized. Four of these clones were real U3 snRNA genes because they were transcribed in frog oocytes and the DNA sequences corresponding to the U3 snRNA were identical to the U3 snRNA of HeLa cells. The nucleotide sequences of four true U3 snRNA genes, 537 nucleotides on the 5'-flanking region and 340 nucleotides on the 3'-flanking region, were found to be identical. In addition, the restriction patterns, upto 2 kb on the 5' side and 2.2 kb on the 3' side, appeared to be same. All the isolated U3 clones, containing 15-20 kb of genomic DNA, contained only one U3 snRNA gene, indicating that the human U3 snRNA genes are several kilobases apart. One of the U3 clones contained a full-length U3 pseudogene. Southern blot analysis of genomic DNA with cloned U3 DNA as probe indicated that human DNA contains two families of U3 genes which differ in their flanking sequences. In the 5' flanking region of human U3 snRNA genes, homology to U-gene promoter element, an octamer motif, the 'U3 box', SP1 binding sites and a consensus 3' box in the 3' flanking region, were observed. These data show that the genomic organization and the sequence motifs that control transcription of human nucleolar U3 snRNA genes are similar to those of human U1 and U2 snRNA genes and suggest common mechanism(s) in the evolution of snRNA genes.

Does the intraesophageal pH probe accurately detect acid reflux? Simultaneous recording with two pH probes in humans

Little is known about the accuracy of intraesophageal pH monitoring, ie, do false negatives occur? This study was designed based on the assumption that if two pH probes are placed equidistant from a distal acid source, and the probes measure different values, then one probe might miss acid if it were there alone. We performed 24-hr intraesophageal pH monitoring in 10 patients with gastroesophageal reflux disease, simultaneously placing two pediatric pH probes (probes A and B) 5 cm proximal to the LES in such close proximity that one would expect only small differences in the acid exposure measured by the probes. However, the amount of acid exposure measured by probes A and B differed greatly in some instances. Individual probe performance does not alone account for these differences, since, when pH recordings were reviewed, one probe was as likely to miss acid exposure as the other. These differences would result in a change in the clinical diagnosis in two of 10 patients. Variability in the number of episodes was great and occurred even when there was concordance in percent acid exposure. These data raise questions about the absolute accuracy of the pH probe as the gold standard in the measurement of gastroesophageal reflux.