Disparate responses to oxidative stress in saprophytic and pathogenic mycobacteria

To persist in macrophages and in granulomatous caseous lesions, pathogenic mycobacteria must be equipped to withstand the action of toxic oxygen metabolites. In Gram-negative bacteria, the OxyR protein is a critical component of the oxidative stress response. OxyR is both a sensor of reactive oxygen species and a transcriptional activator, inducing expression of detoxifying enzymes such as catalase/hydroperoxidase and alkyl hydroperoxidase. We have characterized the responses of various mycobacteria to hydrogen peroxide both phenotypically and at the levels of gene and protein expression. Only the saprophytic Mycobacterium smegmatis induced a protective oxidative stress response analogous to the OxyR response of Gram-negative bacteria. Under similar conditions, the pathogenic mycobacteria exhibited a limited, nonprotective response, which in the case of Mycobacterium tuberculosis was restricted to induction of a single protein, KatG. We have also isolated DNA sequences homologous to oxyR and ahpC from M. tuberculosis and Mycobacterium avium. While the M. avium oxyR appears intact, the oxyR homologue of M. tuberculosis contains numerous deletions and frameshifts and is probably nonfunctional. Apparently the response of pathogenic mycobacteria to oxidative stress differs significantly from the inducible OxyR response of other bacteria.

Identification of a gene involved in the biosynthesis of cyclopropanated mycolic acids in Mycobacterium tuberculosis

Mycolic acids represent a major constituent of the mycobacterial cell wall complex, which provides the first line of defense against potentially lethal environmental conditions. Slow-growing pathogenic mycobacteria such as Mycobacterium tuberculosis modify their mycolic acids by cyclopropanation, whereas fast-growing saprophytic species such as Mycobacterium smegmatis do not, suggesting that this modification may be associated with an increase in oxidative stress experienced by the slow-growing species. We have demonstrated the transformation of the distal cis double bond in the major mycolic acid of M. smegmatis to a cis-cyclopropane ring upon introduction of cosmid DNA from M. tuberculosis. This activity was localized to a single gene (cma1) encoding a protein that was 34% identical to the cyclopropane fatty acid synthase from Escherichia coli. Adjacent regions of the DNA sequence encode open reading frames that display homology to other fatty acid biosynthetic enzymes, indicating that some of the genes required for mycolic acid biosynthesis may be clustered in this region. M. smegmatis overexpressing the cma1 gene product significantly resist killing by hydrogen peroxide, suggesting that this modification may be an important adaptation of slow-growing mycobacteria to oxidative stress.

[Measurement of the reserve function of inspiratory muscle and its clinical significance]

The principles of measuring inspiratory muscle tension-time index (TTim) and the ratio of the works of inspiration over the maximal works of inspiration (Wi/Wi(max)) were investigated and their formulae were deduced, i.e. TTim = (Pi x Ti)/(MIP x Ttot) and Wi/Wi(max) = (Pi x VT)/(MIP x IC). The importance of the inspiratory pressure and the maximal inspiratory pressure (MIP) measured at function residual capacity (FRC) level was emphasized. Both TTim and Wi/Wi(max) were measured in 35 normal subjects and 89 patients with chronic obstructive pulmonary disease (COPD). The results showed that normal value of TTim was 0.0253 +/- 0.0055 which corresponds to the normal value of the diaphragm tension-time index (TTdi = 0.02-0.03) reported by Bellemare. Patients with COPD had a mean TTim much higher than that of normals (P < 0.01). The works of inspiration (Wi) in patients with COPD increased, while the maximal works of inspiration (Wi(max)) declined, so Wi/Wi(max) became significantly greater than that of normals (P < 0.01). The results also showed that there was a linear relationship between Pi/Pimax and TTim or Wi/Wimax (r = 0.7891, 0.9738, 0.6459, 0.9327, P < 0.01). Therefore, we suggest that both TTim and Wi/Wimax can be used as clinical indices to reflect the reserve function of inspiratory muscles.

Association between GRB2/Sos and insulin receptor substrate 1 is not sufficient for activation of extracellular signal-regulated kinases by interleukin-4: implications for Ras activation by insulin

Insulin receptor substrate 1 (IRS-1) mediates the activation of a variety of signaling pathways by the insulin and insulin-like growth factor 1 receptors by serving as a docking protein for signaling molecules with SH2 domains. We and others have shown that in response to insulin stimulation IRS-1 binds GRB2/Sos and have proposed that this interaction is important in mediating Ras activation by the insulin receptor. Recently, it has been shown that the interleukin (IL)-4 receptor also phosphorylates IRS-1 and an IRS-1-related molecule, 4PS. Unlike insulin, however, IL-4 fails to activate Ras, extracellular signal-regulated kinases (ERKs), or mitogen-activated protein kinases. We have reconstituted the IL-4 receptor into an insulin-responsive L6 myoblast cell line and have shown that IRS-1 is tyrosine phosphorylated to similar degrees in response to insulin and IL-4 stimulation in this cell line. In agreement with previous findings, IL-4 failed to activate the ERKs in this cell line or to stimulate DNA synthesis, whereas the same responses were activated by insulin. Surprisingly, IL-4's failure to activate ERKs was not due to a failure to stimulate the association of tyrosine-phosphorylated IRS-1 with GRB2/Sos; the amounts of GRB2/Sos associated with IRS-1 were similar in insulin- and IL-4-stimulated cells. Moreover, the amounts of phosphatidylinositol 3-kinase activity associated with IRS-1 were similar in insulin- and IL-4-stimulated cells. In contrast to insulin, however, IL-4 failed to induce tyrosine phosphorylation of Shc or association of Shc with GRB2. Thus, ERK activation correlates with Shc tyrosine phosphorylation and formation of an Shc/GRB2 complex. Thus, ERK activation correlates with Shc tyrosine phosphorylation and formation of an Shc/GRB2 complex. Previous studies have indicated that activation of ERks in this cell line is dependent upon Ras since a dominant-negative Ras (Asn-17) blocks ERK activation by insulin. Our findings, taken in the context of previous work, suggest that binding of GRB2/Sos to Shc may be the predominant mechanism whereby insulin as well as cytokine receptors activate Ras.

Substrate recognition by human RNase P: identification of small, model substrates for the enzyme

RNase P from HeLa cells can efficiently cleave tRNA precursor molecules in vitro but cannot cleave potential substrates from which the D, anticodon and variable loops and stems of the tRNA moiety have all been removed. However, molecules from which the latter subdomains have been removed individually do serve as substrates. We show here that molecules that contain only a 5' leader sequence, the acceptor stem and the T stem and loop of the tRNA domain, and a bulge as small as one nucleotide downstream from nucleotide 7 in the tRNA sequence at the junction of the two stems, can serve as substrates for human RNase P. The identity of the nucleotide in the bulge is important in determining both the efficiency of the cleavage and the conformation of the substrate and/or the enzyme-substrate complex. We also show that the human enzyme locates the appropriate site for cleavage of its substrates in part by 'measuring' the length of the helices in the acceptor and T stems in both model and natural substrates.

Interaction of neutrophils and endothelium in isolated coronary venules and arterioles

This study reports measurements of porcine neutrophil dynamics in isolated microvessels. Porcine coronary venules and arterioles were isolated, cannulated, and perfused with fluorescently labeled neutrophils at a series of flow velocities. In venules (62.50 +/- 5.41 microns diam) under control conditions, rolling neutrophils were often observed at intraluminal flow velocities ranging from 600 to 6,000 microns/s, and the rolling fraction varied inversely as a function of flow velocity. There was no significant adherence under the control conditions at any of the various flow velocities. Pretreatment of the neutrophils with human recombinant complement 5a (C5a, 10(-8) M) increased adherence at low flow velocities but did not alter the rolling fraction. In contrast to venules, rolling neutrophils were not observed in arterioles (58.80 +/- 5.6 microns diam). Furthermore, neutrophils that were pretreated with C5a did not adhere to the arteriolar endothelium even at low flow velocities. We suggest that 1) isolated microvessels perfused with fluorescently labeled neutrophils are suitable models for the study of the interaction between neutrophils and the microvascular endothelium, 2) shear force plays an important role in neutrophil rolling in coronary venules but is not the major factor that prevents neutrophil rolling and adherence in arterioles, and 3) C5a causes neutrophil adherence in venules but not in arterioles, indicating that different mechanisms underlie the interaction between neutrophils and endothelium in venules and arterioles.

Tyrosine kinases regulate the cytoskeletal attachment of integrin alpha IIb beta 3 (platelet glycoprotein IIb/IIIa) and the cellular retraction of fibrin polymers

Integrins promote cell-substratum and cell-cell adhesion by acting as transmembrane linker molecules between extracellular adhesion proteins and the actin-rich cytoskeleton. The integrin alpha IIb beta 3 (platelet glycoprotein IIb/IIIa) is essential for platelet spreading, aggregation, fibrin clot retraction, and for the transduction of extracellular signals. We examined the effect of the specific tyrosine kinase inhibitor herbimycin A on integrin and cytoskeletal-mediated events in thrombin-stimulated platelets. Incubation of washed platelets for 24 h with herbimycin A (5 microM) abolished the thrombin-stimulated cytoskeletal enzyme activity of pp60c-src in parallel with a reduction in the tyrosine phosphorylation of multiple platelet proteins, as assessed with anti-phosphotyrosine immunoblots. However, thrombin-induced activation of protein kinase C and the production of thromboxane A2 were not altered by herbimycin A. Despite the absence of cytoskeletal pp60c-src enzyme activity, platelet shape change, aggregation, and serotonin release were unaltered following platelet stimulation with thrombin (0.05-1.0 unit/ml). Herbimycin A-treated platelets also demonstrated normal platelet aggregation in response to collagen (5 micrograms/ml), ionophore A23187 (2 microM), and ADP/adrenaline (10 microM each). However, the ability of herbimycin A-treated platelets to retract fibrin gels was significantly reduced. This defect in clot retraction was associated with reduced incorporation of integrin alpha IIb beta 3 into the cytoskeletal fraction of thrombin-aggregated platelets. Our studies suggest that tyrosine kinases in platelets regulate the cytoskeletal attachment of alpha IIb beta 3, as an essential process for the transmission of cellular contractile forces to fibrin polymers.

Adhesion receptor activation of phosphatidylinositol 3-kinase. von Willebrand factor stimulates the cytoskeletal association and activation of phosphatidylinositol 3-kinase and pp60c-src in human platelets

The cytoskeleton participates in the coordinated regulation of intracellular signaling molecules, following agonist stimulation of cells. We have demonstrated that von Willebrand factor (vWF) induced the cytoskeletal association and activation of phosphatidylinositol 3-kinase (PtdIns 3-kinase) in human platelets. The activation of PtdIns 3-kinase coincided with the tyrosine phosphorylation of multiple platelet proteins, as assessed by anti-phosphotyrosine immunoblotting. One of these tyrosine-phosphorylated proteins, pp60c-src, became specifically enriched in the cytoskeletal fraction of vWF-stimulated platelets. The vWF-stimulated cytoskeletal association of PtdIns 3-kinase and pp60c-src required platelet stirring and aggregation, was specifically blocked by an anti-GPIb monoclonal antibody, and was not observed in platelets lacking the glycoprotein Ib/IX complex (Bernard-Soulier syndrome). Pretreatment of normal platelets with 5 mM EDTA (37 degrees C for 90 min) or RGDS (2 mM), which disrupts the binding of various adhesive proteins to platelet integrins and inhibits fibrinogen-mediated platelet aggregation, did not alter the vWF-stimulated activation and cytoskeletal association of PtdIns 3-kinase and pp60c-src. Pretreatment of platelets with acetylsalicylic acid (1 mM) completely abolished vWF-stimulated production of thromboxane A2, dense granule release, and the activation of protein kinase C, without altering the activation and cytoskeletal translocation of PtdIns 3-kinase and pp60c-src. Our results suggest that vWF binding to the platelet adhesion receptor glycoprotein Ib/IX can mediate activation and translocation of both tyrosine and lipid kinase(s) independent of other agonists.

Development of a central matching system for the allocation of cadaveric kidneys: a simulation of clinical effectiveness versus equity

OBJECTIVES

1) To develop a computer-based simulation to prospectively study the impacts of explicitly incorporating different equity criteria into the process of allocating kidneys to recipients, given the scarcity of this resource. 2) To assess the tradeoffs between systems that allocate kidneys based only on medical criteria, systems that allocate kidneys based only on equity criteria, and systems that consider both medical and equity criteria.

METHODS

A computer-based simulation was developed that describes the flows of patients and kidneys. This model provides information at various time points about the number of patients in the system who are awaiting transplants, the number of kidneys available for transplantation, the number of transplantations performed for each matching algorithm, and the number of kidneys discarded (when applicable), as well as the means and standard deviations of the HLA-match scores, number of days from registration to transplantation, and number of days (from registration) of those who are still waiting for transplants. Five different matching algorithms were compared, ranging from determination of the allocation by a single medical criterion (i.e, HLA match) to determination by a single equity criterion (i.e., relative position in the waiting queue). The remaining algorithms represent different strategies of weighting these two considerations. Estimates regarding the main parameters of the model were derived utilizing data collected through the Multiple Organ Retrieval and Exchange Programme of Ontario, Canada.

RESULTS

The simulation was set to run for a period of ten years. A tradeoff between graft survival (or improved HLA matching) and equal treatment of patients regardless of their likelihood to benefit was found. It is clear that an algorithm that allocates kidneys based only on temporal location of patient on the waiting list is likely to be unacceptable because of the very poor average HLA-match scores that it yields. Pool size was found to be a major determinant in the attainment of optimal matching from a medical perspective.

CONCLUSIONS

1) The final choice about any allocation algorithm to be used requires that a value judgment be made, i.e., how great a reduction in HLA-match score should be traded in order to improve equity score (or vice versa). 2) A computer-based simulation model is a feasible way to prospectively test the impact of any given allocation algorithm on any given system.

Selection of guide sequences that direct efficient cleavage of mRNA by human ribonuclease P

Any RNA, when in a complex with another oligoribonucleotide known as an external guide sequence (EGS), can become a substrate for ribonuclease P. Simulation of evolution in vitro was used to select EGSs that bind tightly to a target substrate messenger RNA and that increase the efficiency of cleavage of the target by human ribonuclease P to a level equal to that achieved with natural substrates. The most efficient EGSs form transfer RNA precursor-like structures with the target RNA, in which the analog of the anticodon stem has been disrupted, an indication that selection for the optimal substrate for ribonuclease P yields an RNA structure different from that of present-day transfer RNA precursors.

66A-078:a kappa-opiate receptor agonist for amelioration of spinal spasticity

The effect and mechanism of kappa opiate receptor agonist and high-frequency electrostimulation of acupoints in treating spinal spasticity were studied. The spinal spastic models were made by gradual mechanical compression on the cervical spinal cord of rabbits. 24 prepared rabbits were divided into 3 groups randomly, and each group with 8 rabbits was given intrathecally kappa-receptor agonist 66A-078, kappa-receptor antagonist +66A-078 and normal saline respectively. The degree of spasticity was quantified by both clinical score and electrophysiological examinations. The result showed that the spasticity was markedly inhibited by intrathecal injection of 66A-078 and that the kappa-receptor antagonist (naloxone) reversed this effect. We can infer that the antispastic effect of 66A-078 is mediated by kappa-receptors. This result is helpful in explaining the immediate antispastic mechanism of high-frequency electrostimulation of acupoints discussed in previous study.

Human RNaseP RNA and nucleolar 7-2 RNA share conserved 'To' antigen-binding domains

RNase P in both prokaryotes and eukaryotes is a ribonucleoprotein that cleaves tRNA precursors to generate the 5' termini of the mature tRNAs. Many patients with autoimmune diseases produce antibodies against a 40 kDa protein (designated To or Th antigen) which is an integral component of eukaryotic RNaseP as well as nucleolar 7-2 RNP which is identical to the mitochondrial RNA processing (MRP) RNP. Interestingly, the To antigen found in human cells and the C5 protein, the only protein component of E. coli RNaseP, are antigenically related. In this study, we show that a 56 nucleotide-long sequence, corresponding to nucleotides 20-75 near the 5' end of human RNaseP RNA, is sufficient to bind the To antigen. We previously showed that the human To antigen binds to a short distinct structural domain near the 5' end of human 7-2/MRP RNA. There is no obvious primary sequence homology between the To antigen binding sites in RNaseP RNA and 7-2/MRP RNA; however, these sequences are capable of assuming a similar secondary structure which corresponds to the recently proposed 'cage' structure for RNaseP RNAs and 7-2/MRP RNA (Forster and Altman (1989) Cell 62: 407-409). These data are supportive of the idea that these two RNAs may have evolved from a common progenitor molecule.

Transcutaneous electrical nerve stimulation for treatment of spinal spasticity

Thirty-two patients with spinally originated muscle spasticity were treated with a transcutaneous electrical nerve stimulator, the Han's acupoint nerve stimulator (HANS) via skin electrodes placed over the acupoints on the hand and leg. High frequency (100 Hz), but not the low frequency (2 Hz), stimulation was effective in ameliorating muscle spasticity. While the therapeutic effect lasted for only 10 minutes in the first treatment, it became consolidated after consecutive daily treatment for 3 months. The anti-spastic effect induced by high frequency electrical stimulation can be partially reversed by a high dose of naloxone. The results suggest that the anti-spastic effect elicited by peripheral electrical stimulation is mediated, at least in part, by the endogenous opioid ligand interacting with the kappa opiate receptors, most probably dynorphin, in the central nervous system.

Sports causing most injuries in Hong Kong

A prospective survey was carried out on 2293 patients attending the Sports Injury Clinic in the Prince of Wales Hospital between May 1984 and December 1990. A Sports Injury Report Form was completed for each patient. Subjects in this study represent a group of nonprofessional and non-élite athletes in a metropolitan area. Soccer, basketball, volleyball, long-distance running and cycling in descending order were the five most common sports causing injury. Different sports produced different injury patterns. In four of the five sports, the knee (27.27-50.47%) and the ankle (16.78-24.67%) were the commonest sites of injury. In cycling, the face (19.46%) was the commonest site of injury. There was a higher injury rate to the lower than the upper limb in soccer, basketball, volleyball and long-distance running, with a ratio of upper- to lower-limb injury ranging from 1:1.13 to 1:46.10. In cycling, upper limb injury was more frequent (upper- to lower-limb injury ratio was 1:0.53). Sprain was the commonest injury overall (44.60%). It was also the commonest injury condition in volleyball (55.15%), basketball (55.34%), soccer (51.41%) and long-distance running (39.33%). In cycling, abrasion (24.83%) was commonest.

[Research on anti-idiotypic antibodies to bovine abortus]

Based on the establishment of McAbs to a local Brucella strain S85A, the McAb A7 was selected and tested as a protective one. Using A7 to immunize rabbits, we got high titer anti-idiotypic antibodies which were then proved to possess internal image by competitive inhibiting ELISA and catch blocking ELISA. The anti-idiotypic antibodies were then purified and mixed with glycerin to immunize guinea pigs and mice. The results showed that: immunized guinea pigs and mice had produced certain titer antibodies to Brucella. 79.2% of immunized guinea pigs had been protected from the challenge of 544A 4 months later from primary immunization. The number of T ANAE+ in peripheral blood of immunized mice had increased significantly compared to controls. These results suggest that the anti-idiotypic antibodies not only possess the antigen internal image but have the available immunogenicity stimulate animals producing Ab3 and make them get free from the infection.

Permeability to albumin in isolated coronary venules

This study reports measurements of albumin permeability in isolated coronary venules. The isolated microvessel technique allows the quantification of transmural exchange of macromolecules under tightly controlled physical and chemical conditions. Transvenular exchange of albumin was studied in isolated coronary venules during alterations in filtration rate caused by changes in intravascular pressure. The apparent permeability coefficient of albumin (Pa) at an intraluminal pressure of 11 cmH2O was 3.92 +/- 0.43 x 10(-6) cm/s. Elevating intraluminal pressure to 16 and 21 cmH2O increased Pa to 5.13 +/- 0.57 x 10(-6) and 6.78 +/- 0.66 x 10(-6) cm/s, respectively. Calculation of the true diffusive permeability coefficient of albumin (Pd) at zero filtration rate was 1.54 x 10(-6) cm/s. The product of hydraulic conductance (Lp) and (1 - sigma), where sigma is the solute reflection coefficient, was 3.25 x 10(-7) cm.s-1 x cmH2O-1. At a net filtration pressure of 4-5 cmH2O, diffusion accounts for > 60% of total albumin transport across the venular wall. Transmural albumin flux is very sensitive to filtration rate, rising 6.7% for each cmH2O elevation of net filtration pressure. At 11 cmH2O net filtration pressure, convection accounts for nearly 70% of net albumin extravasation from the venular lumen. We suggest that the isolated coronary venule is a suitable preparation for the study of solute exchange in the heart.

Purification and characterisation of a snake venom phospholipase A2: a potent inhibitor of platelet aggregation

An inhibitor of human platelet aggregation was identified from the venom of an Australian Copperhead snake, Austrelaps superba, as a novel phospholipase A2. The inhibitor was purified to homogeneity by chromatography on Q-Sepharose, S-Sepharose and C8 reverse phase HPLC. The purified phospholipase A2 has a molecular weight of 15 kDa as assessed by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). N-terminal sequence analysis of the platelet inhibitor revealed 70-80% sequence identity to other previously described secretory phospholipase A2. Phospholipase activity of the purified protein was confirmed by the ability of the enzyme to hydrolyse lecithin. Pretreatment of the purified protein with the specific phospholipase A2 inhibitor p-bromophenacyl bromide, resulted in abrogation of both its enzyme and platelet inhibitory activity. The phospholipase A2 inhibited platelet aggregation and serotonin release, induced by a variety of platelet agonists, in a time and dose dependent manner.

Hong Kong Sports Institute: sports medicine and science from theory to practice

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Disruption by methylmercury of membrane excitability and synaptic transmission of CA1 neurons in hippocampal slices of the rat

In order to examine the effects of methylmercury (MeHg) on central synaptic transmission, field potentials were recorded in the CA1 neurons of hippocampal slices by using extracellular microelectrode recording techniques. After stimulation of Schaffer collaterals at low frequency (0.25 Hz), population spikes and excitatory postsynaptic potentials (EPSPs) were recorded at the cell bodies and apical dendrites of CA1 pyramidal cells, respectively. Antidromically activated population spikes were also recorded at the cell bodies of CA1 pyramidal cells by stimulating the alveus. Long-term potentiation (LTP) was induced by application of brief high-frequency stimulation (15 trains of four stimuli per train at 100 Hz) after 25 min of population spike baseline recordings. MeHg was applied to slices acutely by bath perfusion with artificial cerebrospinal fluid (ACSF). At 20-500 microM, MeHg significantly increased and then decreased the amplitudes of, or blocked, the population spikes, EPSPs, and antidromically activated population spikes. Time to increase and time to block of these field potentials were concentration-dependent. Exposure of slices to 4 microM MeHg for 180 min increased but did not reduce the amplitudes of population spikes, EPSPs, or antidromically activated population spikes. The effects of MeHg on population spikes induced by either orthodromic or antidromic stimulation were similar. In the absence of MeHg, application of high-frequency stimulation increased population spike amplitudes by 60-100%. This effect (LTP) could be sustained for more than 2 hr in the absence of MeHg. When 100 microM MeHg was applied concomitantly with high-frequency stimulation, the population spike amplitudes were increased by an additional 20-50% based on the already elevated population spike amplitude by high-frequency stimulation. Subsequently, population spike amplitudes were reduced and finally blocked in a manner similar to the effect of MeHg on population spikes recorded without high-frequency stimulation. Application of MeHg (100 microM) for 20 min prior to high-frequency stimulation did not prevent induction of LTP even though the population spike amplitudes had been decreased by more than 10% of the control level, suggesting that MeHg may not alter induction of LTP. Reversibility of the effects of MeHg was examined by washing slices with MeHg-free ACSF or 1 mM D-penicillamine for 60-120 min after MeHg treatment. Washing slices with MeHg-free ACSF caused at best partial reversal of effects of MeHg. D-Penicillamine, a chelator of MeHg, completely reversed the effects of MeHg on EPSPs but only partially reversed the effects of MeHg on population spikes, antidromically activated population spikes, and LTP.(ABSTRACT TRUNCATED AT 400 WORDS)

Histamine increases venular permeability via a phospholipase C-NO synthase-guanylate cyclase cascade

In this study, we hypothesized that histaminergic increases in venular permeability result from a cascade triggered by activation of phospholipase C (PLC), inducing the synthesis of nitric oxide (NO) and activating guanylate cyclase. The apparent permeability coefficient to albumin (Pa) was measured in isolated porcine coronary venules subjected to constant flow and hydrostatic and oncotic pressures. Histamine (2.5, 5, and 10 microM) transiently and progressively increased Pa. The PLC inhibitor 2-nitro-4-carboxyphenyl N,N-diphenylcarbamate (NCDC; 100 microM) decreased baseline permeability and abolished the effect of histamine. The NO synthase inhibitor NG-monomethyl-L-arginine (L-NMMA; 10 microM) and the guanylate cyclase inhibitor 6-anilinoquinoline-5,8-quinone (LY 83583; 10 microM) also blocked the histamine-induced hyperpermeability. L-Arginine (3 mM) reversed the inhibition by L-NMMA. NG-monomethyl-D-arginine did not influence the effect of histamine. Furthermore, sodium nitroprusside (10 microM) augmented Pa by two- to threefold; this effect was blocked in the presence of LY 83583 but not altered in the presence of NCDC. The results suggest that histamine increases coronary venular permeability by a direct action on the venular endothelial cells through a PLC-NO synthase-guanylate cyclase-signaling cascade.

Real-time coherent image differentiation using a self-pumped phase conjugator with Cu:KNSBN

A technique for real-time coherent image differentiation is described in a device consisting of a self-pumped phase conjugator that uses a copper-doped potassium sodium strontium barium niobate crystal. We demonstrate the proposed technique.

The Johnson antishear device and standard shin pad in the isokinetic assessment of the knee

Isokinetic training and assessment of the knee joint has been the mainstay of rehabilitation, especially in patients with anterior cruciate ligament deficiency. Besides the original shin pad used, the antishear device was introduced by Johnson in 1982. This device has been shown biomechanically to prevent excessive anterior translation of force on the tibia during training. However, there is a need to compare the antishear device and the standard shin pad in the isokinetic assessment. Hence, the major objective of this study is to define, if any, the difference in patient assessment between the new double pad device and the old single shin pad. Ten subjects with no previous history of injury on either knee were tested with the Cybex Isokinetic Dynamometer. There were four men and six women and the mean age was 25.2 years. They were randomized into different test sequences with different shin pads at different speeds. Correlation and paired t tests (P) were performed to find out the correlation and difference between the two devices. There was significant difference in performance assessment between the two devices in knee extension (P < 0.05) but no significant difference in knee flexion (P > 0.05). There was also a high correlation (r > 0.75) between the two devices. It is concluded that because of the significant difference of data generated between the two devices, it is important to select one single device with each patient during a series of testings.

Enhanced self-pumped phase conjugation from 16 degrees -cut KNSBN:Cu

With the maximum coupling coefficient and high internal reflection conditions, the self-pumped phase-conjugation reflectivity of copper-doped potassium sodium strontium barium niobate (KNSBN:Cu) is increased with 16 degrees -cut samples. The response time is also shortened. The resolution property of 16 degrees -cut KNSBN:Cu is determined and a distorted image is corrected by using the 16 degrees -cut sample.

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.