[Comparative study of conventional CT and spiral CT in diagnosis of lung cancer]

OBJECTIVE

To observe and compare the findings of lung cancer with conventional CT and spiral CT.

METHODS

One hundred and thirty-four cases of pathologicalty confirmed lung cancer, including 56 centrally located and 78 peripherally located lung cancer, were examined by conventional CT and spiral CT, and their findings compared.

RESULTS

In 30 of the 56 cases with central lung cancer, the lesion was located in the right bronchus and in 26 of them the lesion was in the left bronchus. On spiral CT, the display rate of obstructive findings and invasion to big vessels in the mediastinum was higher than that on conventional CT. There was no remarkable difference in density of the lesion and detection of metastasis in hilar and mediastinal lymph nodes between conventional and spiral CT. In 34 of the 78 cases with peripheral lung cancer, the lesion was in the right lung and in 44 was the lesion in the left lung. Calcification, air-bronchogram, cavity and pleural indentation of the lesion in the peripheral lung cancer were better displayed by spiral than by conventional CT.

CONCLUSION

Spiral CT is superior to conventional CT in the observation of signs characteristic of central and peripheral lung cancers.

Choline modulates cardiac membrane repolarization by activating an M3 muscarinic receptor and its coupled K+ channel

Choline is a necessary substrate of the lipid membrane and for acetylcholine synthesis. Accumulating evidence indicates that besides being a structural component, choline is also a functional modulator of the membrane. It has been shown to be a muscarinic acetylcholine receptor (mAChR) agonist and can induce a novel K+ current in cardiac cells. However, the potential role of choline in modulating cardiac functions remained unstudied despite that mAChRs are known to be important in regulating heart functions. With microelectrode techniques, we found that choline produced concentration-dependent (0.1 approximately 10 mm) decreases in sinus rhythm and action potential duration in isolated guinea pig atria. The effects were reversed by 2 nm 4DAMP (an M3-selective antagonist). Whole-cell patch-clamp recordings in dispersed myocytes from guinea pig and canine atria revealed that choline is able to induce a K+ current with delayed rectifying properties. The choline-induced current was suppressed by low concentrations of 4DAMP (2 approximately 10 nm). Antagonists toward other subtypes (M1, M2 or M4) all failed to alter the current. The affinity of choline (Kd) at mAChRs derived from displacement binding of [3H]-NMS in the homogenates from dog atria was 0.9 mm, consistent with the concentration needed for the current induction and for the HR and APD modulation. Our data indicate that choline modulates the cellular electrical properties of the hearts, likely by activating a K+ current via stimulation of M3 receptors.

[CT evaluation of the primary extracranial neoplastic diseases eroding the central skull base]

OBJECTIVE

To evaluate the central skull base erosion caused by primary extracranial mass lesions with CT.

METHODS

Forty-nine patients (33 males and 16 females; mean, 40.2 years) suffered from the primary extracranial neoplastic diseases with middle skull base involvement were divided into two groups: group I (10 cases), primary osseous lesions of the central skull base and group II (39 cases), primary maxillofacial neoplasms. All lesions were confirmed histopathologically by surgery and biopsy.

RESULTS

Four invasion patterns of the central skull base were identified on CT: I. resorption of the cortical bone (30 cases), including outer cortical margin destruction in 16 cases (group II lesions) and both inner and outer laminae resorption in 14 cases (4 group I lesions and 10 groups II lesions). II. ossification and thickening of the skull base (4 group I cases, all were fibrous dysplasia) III. erosive enlargement of the ovale and rotundam foramina (9 group II cases). IV. combined sclerosis and resorption of the skull base (6 cases, 2 group I lesions and 4 group II lesions). Involvement of the intracranial structures embraced the cavernous sinus (n = 12; group II lesions), temporal lobe (n = 11; 5 group I lesions and 6 group II lesions), and pituitary (n = 2, group II lesions). CT demonstrated the following central skull base structures were eroded: greater wing of sphenoid bone (n = 34), sphenoid body (n = 22), sphenoid process (n = 23), petrous bone (n = 15), and articular fossa of the temporal bone (n = 8).

CONCLUSION

Osseous lesions originating from the central skull base have various CT manifestations. The cortical resorption of the central skull base may be regarded as a main pattern of bone erosion caused by primary maxillofacial neoplasms, and most of them have lesions involve the greater wing of sphenoid bone through the deeper maxillofacial spaces, such as the infratemporal, pterygopalatine and parapharyngeal spaces.

Formation of phospholipid hydroperoxides and its inhibition by alpha-tocopherol in rat brain synaptosomes induced by peroxynitrite

Peroxynitrite resulted from the reaction of nitric oxide and superoxide anion has been implicated in the genesis of neurotoxicity. In this study, the oxidation of phospholipids in rat brain synaptosomes induced by peroxynitrite generated from 3-morpholinosydnonimine (SIN-1) was studied in vitro. The formation and accumulation of phospholipid hydroperoxides, including phosphatidylcholine hydroperoxide (PCOOH) and phosphatidyl-ethanolamine hydroperoxide (PEOOH) in rat brain synaptosomes induced by peroxynitrite, were observed. PEOOH and PCOOH were formed rapidly and SIN-1 concentration-dependently. The hydroperoxides formed in synaptosomes were unstable and it was suggested that phospholipase A2 played a role in degradation of the hydroperoxides. The endogenous alpha-tocopherol acted as a potent antioxidant. It was oxidized very rapidly and concentration-dependently by SIN-1 to alpha-tocopheryl quinone. Furthermore, uric acid was found to be an effective antioxidant in inhibiting oxidative damage to synaptosomal lipids induced by SIN-1. The results provide direct evidence to show that peroxynitrite can not only deplete alpha-tocopherol, but also cause production of phospholipid hydroperoxides resulting in disrupted brain tissue.

Template-imprinted nanostructured surfaces for protein recognition

Synthetic materials capable of selectively recognizing proteins are important in separations, biosensors and the development of biomedical materials. The technique of molecular imprinting creates specific recognition sites in polymers by using template molecules. Molecular recognition is attributed to binding sites that complement molecules in size, shape and chemical functionality. But attempts to imprint proteins have met with only limited success. Here we report a method for imprinting surfaces with protein-recognition sites. We use radio-frequency glow-discharge plasma deposition to form polymeric thin films around proteins coated with disaccharide molecules. The disaccharides become covalently attached to the polymer film, creating polysaccharide-like cavities that exhibit highly selective recognition for a variety of template proteins, including albumin, immunoglobulin G, lysozyme, ribonuclease and streptavidin. Direct imaging of template recognition is achieved by patterning a surface at the micrometre scale with imprinted regions.

Pteridine analysis in urine by capillary electrophoresis using laser-induced fluorescence detection

Pteridines are a class of compounds excreted in urine, the levels of which are found to elevate significantly in tumor-related diseases. For the first time, we have developed a method, based on high-performance capillary electrophoresis (HPCE) and laser-induced fluorescence (LIF) detection, to monitor the pteridine levels in urine. HPCE provides better separation than high-performance liquid chromatography and the LIF detector enables us to detect minute amounts of pteridines in body fluid. Eight different pteridine derivatives were well separated in 0.1 M Tris-0.1 M borate-2 mM EDTA buffer (pH 8.75) using a 60-cm fused-silica capillary (50-micron i.d., 35-cm effective length), six of which were detected and characterized in urine samples from normal persons and different cancer patients. The detection limits of these pteridines are under 1 x 10(-10) M. The levels of neopterin, pterine, xanthopterin, and pterin-6-carboxylic acid were found to be significantly elevated in urine excreted by cancer patents, while the level of isoxanthopterin dropped in these patients. No significant change of biopterin level was found between healthy individuals and cancer patients. This method can be used in clinical laboratories either for cancer monitoring or for precancer screening.

[Detection and significance of interleukin-16 in sputa from patients with bronchial asthma]

OBJECTIVE

To explore the significance of in the terleukin-16 (IL-16) in pathogenesis of bronchial asthma.

METHODS

Induced sputum samples were obtained from 12 allergic asthmatics, 8 non-allergic asthmatics, 10 non-asthma allergic and 10 non-asthma non-allergic normal subjects. ELISA was used to determine the concentrations of IL-16 in sputum, and CD4+ T cells and activated eosinophils (EG2 cells) in sputum were detected by immunostaining.

RESULTS

IL-16 levels in both allergic and non-allergic asthmatics were much higher than those in non-asthma allergic or non-asthma non-allergic normal subjects. Effective anti-asthma treatment led to a significant decrease in IL-16 levels in patients with acute asthma. It was also found that the percentages of CD4+ and EG2 cells were all positively correlated to IL-16 levels.

CONCLUSIONS

IL-16 is involved in the asthmatic process by recruiting CD4+ T cells and thus plays an important role in CD4+ cell-dependent eosinophilic inflammation in asthmatic airways.

Potential molecular basis of different physiological properties of the transient outward K+ current in rabbit and human atrial myocytes

The properties of the transient outward current (Ito) differ between rabbit and human atrial myocytes. In particular, rabbit Ito is known to recover more slowly than its human counterpart and to show much more frequency dependence. To assess the possibility that these physiological differences may reflect differing expression of K+ channel subunit gene products, we used a combination of whole-cell voltage-clamp, heterologous expression, pharmacological, antisense, and Western blot techniques. The inactivation of Ito in rabbit atrial myocytes was significantly slowed by hydrogen peroxide, with human Ito being unaffected. Use-dependent unblocking with 4-aminopyridine was not seen for rabbit Ito nor for Kv1.4 currents in Xenopus oocytes, whereas human Ito showed strong use-dependent unblock (as did Kv4 currents). Western blots indicated the presence of Kv4 proteins in both human and rabbit atrial membranes, but Kv1.4 was only detected in the rabbit. Antisense oligodeoxynucleotides directed against Kv4.3, Kv4.2, or Kv1.4 subunit sequences significantly inhibited Ito current density in cultured rabbit atrial myocytes, whereas only Kv4.3 antisense significantly inhibited Ito in human cells. Neither mismatch oligodeoxynucleotides nor vehicle altered currents in either species. We conclude that, unlike human atrial myocytes, rabbit atrial myocytes express Kv1.4 channel subunits, which likely contribute to a number of important physiological differences in Ito properties between the species. To our knowledge, these studies constitute the first demonstration of a functional role for Kv1.4 channels in cardiac membranes and provide insights into the molecular mechanisms of an important cardiac repolarizing current.

Embryo-dependent induction of embryo receptivity in the mouse endometrium

The effect of intraoviductal embryos on endometrial receptivity was studied by intraendometrial and intrauterine embryo transfer. Five-week-old female ICR mice were mated after superovulation; a vaginal plug confirmed day 1 of pregnancy. On day 4 (90 h after hCG injection), blastocysts were collected and transferred to pseudopregnant female mice and to recipient mice in which the uterotubal junction had been ligated bilaterally on day 1 of pregnancy. Three embryos per uterine horn, a total of six embryos per recipient mouse at days 1-6, were transferred to the endometrium or uterine cavity and implantation and pregnancy rates were calculated. The implantation rate for intraendometrial embryo transfer to recipients of days 3, 5 and 6 was significantly higher for uterotubal junction-ligated mice (72.2, 20.8 and 9.7%, respectively) than for pseudopregnant mice (55.0, 8.3 and 0.0%, respectively). The implantation rate for intrauterine embryo transfer to recipients at days 2, 5 and 6 was significantly higher for uterotubal junction-ligated mice (11.1, 25.0 and 8.3%, respectively) than for pseudopregnant mice (0.0, 3.3 and 0.0%, respectively). Uterotubal junction-ligated mice achieved implantation and bore neonates by intrauterine embryo transfer on days 2 and 6, whereas no implantation was achieved in pseudopregnant mice. The difference in implantation rate could not be explained by a difference in progesterone concentration between the groups. The distribution of proliferating cells in the endometrium was also studied immunohistochemically by use of anti-proliferating cell nuclear antigen (PCNA) antibody in the recipient mice. PCNA-positive cells were more abundant in uterotubal junction-ligated mice and demonstrated a marked extension from the epithelium to the stroma over time, in contrast to those in pseudopregnant mice. These findings indicate that an intraoviductal embryo exerts a biological effect by sending a signal to the endometrial epithelium and stroma, thus facilitating endometrial receptivity to the embryo and improving the rate of implantation.

Identification and characterization of multiple subtypes of muscarinic acetylcholine receptors and their physiological functions in canine hearts

M2 receptors have long been believed to be the only functional subtype of muscarinic acetylcholine receptor (mAChR) in the heart, although recent studies have provided evidence for the presence of other subtypes. We performed a detailed study to clarify this issue. In the presence of tetramethylammonium (1 microM to 10 mM), a novel K+ current with both delayed rectifying and inward rectifying properties (IKTMA) was activated in single canine atrial myocytes. 4-Aminopyridine (0.05-2 mM) also induced a K+ current (IK4AP) with characteristics similar to but distinct from those of IKTMA. Both IKTMA and IK4AP were abolished by 1 microM atropine. IK4AP, but not IKTMA, was minimized by treatment with pertussis toxin. IKTMA was markedly decreased by 4-diphenylacetoxy-N-methylpiperidine methiodide (a selective antagonist for M3 subtype) but was not altered by pirenzepine (for M1), methoctramine (for M2), and tropicamide (for M4). Tropicamide substantially reduced IK4AP, but the antagonists for other mAChR subtypes had no effects on IK4AP. By comparison, IKACh (ACh-induced K+ current) was significantly depressed by methoctramine but was unaltered by other antagonists. Results from displacement binding of [methyl-3H]N-scopolamine methyl chloride with pirenzepine, methoctramine, 4-diphenylacetoxy-N-methylpiperidine methiodide, or tropicamide revealed the coexistence of multiple mAChR subtypes in canine atrium. Cloning of cDNA fragments and detection of mRNAs coding for M2, M3, and M4 provided further supporting evidence. Our results suggest that 1) multiple subtypes of mAChRs (M2/M3/M4) coexist in the dog heart and 2) different subtypes of mAChRs are coupled to different K+ channels. Our findings represent the first functional evidence for the physiological role of cardiac M3 and M4 receptors.

Demonstration of phase correlation in multiwavelength mode-locked semiconductor diode lasers

Wideband spectral phase correlation is demonstrated from a multiwavelength mode-locked semiconductor laser. By use of frequency-resolved optical gating techniques, significant phase correlation was observed between multiple intracavity oscillating wavelengths, with wavelength separations of ~1 nm . The resultant temporal characteristics show a substantial modulation owing to the spectral coupling induced by intracavity-generated four-wave mixing. This result may lead to novel methods for directly generating ultrafast subpicosecond optical pulse sequences with spectrally tailored amplitude and phase characteristics from actively mode-locked semiconductor lasers.

Different effects of simple anoxic lactic acidosis and simulated in vivo anoxic acidosis on turtle heart

We compared responses of turtle heart at 20 degrees C to an anoxic lactic acidosis solution (LA) containing 35 mM lactic acid in an otherwise normal turtle Ringers equilibrated with 3% CO2/97% N2 at pH 7.0) to a solution simulating in vivo anoxic acidosis (VA), with elevated concentrations of lactate, Ca2+, Mg2+, and K+, and decreased Cl-, equilibrated with 10.8% CO2/89.2% N2 at pH 7.0. We examined mechanical properties on cardiac muscle strips and determined intracellular pH (pHi) and high energy phosphates on perfused hearts using 31P-NMR. Maximum active force (Fmax) and the maximum rate of force development (dF/dtmax) of muscle strips were significantly higher during VA than during LA superfusion. An elevation of Ca2+ alone (to 6 mM) in LA significantly increased both Fmax and dF/dtmax but the effects diminished toward the end of the exposure; however, hypercapnic anoxic lactic acidosis (addition of 20 mM HCO3- to LA, equilibrated with 10.8% CO2/89.2% N2, pH 7.0) did not significantly affect Fmax or dF/dtmax. During VA perfusion, pHi (6.73 +/- 0.01) was significantly higher than that during LA perfusion (pHi 6.69 +/- 0.013), but the difference is probably too small to have physiological significance. ATP, creatine phosphate, and inorganic phosphate were not significantly different in the two anoxic solutions. We conclude that the reduction of cardiac mechanical function in vivo is minimized by the integrated effects of changes of ionic concentrations, but the observed changes in Ca2+ and pHi cannot fully explain the effect.

Dynamics and modeling on fermentative production of poly (beta-hydroxybutyric acid) from sugars via lactate by a mixed culture of Lactobacillus delbrueckii and Alcaligenes eutrophus

The mixed culture system was considered in the present research where sugars such as glucose were converted to lactate by Lactobacillus delbrueckii and the lactate was converted to poly beta-hydroxybutyrate (PHB) by Alcaligenes eutrophus in one fermentor. For the modeling of the effect of NH3 concentration on the cell growth of A. eutrophus and PHB production rates, metabolic flux distributions were computed at two culture phases of cell growth and PHB production periods. It was found that the NADPH, generated through isocitrate dehydrogenate in TCA cycle, was predominantly utilized for the reaction from alpha-ketoglutalate to glutamate when NH3 was abundant, while it tended to be utilized for the PHB production through acetoacetyl CoA reductase as NH3 concentration decreased. This phenomenon was reflected in the development of mathematical model. In the mixed culture experiments, the two phases were observed, namely the lactate production phase due to L. delbrueckii and the lactate consumption phase due to A. eutrophus. The lactate concentration could be estimated on-line by the amount of NaOH solution and HCl solution supplied to keep the culture pH at constant level. Several mixed culture experiments were conducted to see the dynamics of the system. Finally, a mathematical model which can describe the dynamic behavior of the present mixed culture was developed and the model parameters were tuned for fitting the experimental data. The model may be used for several purposes such as control, optimization, and understanding process dynamics etc.

[Effects of laminin on the invasive and metastatic behaviors of human salivary adenoid cystic carcinoma cell lines]

OBJECTIVE

To study the effect of laminin (LN) on invasive and metastastic behaviors of salivary adenoid cystic carcinoma (Acc) cell lines.

METHODS

Immunohistochemistry, Boyden chamber in vitro motility, and adhesion test were used. LN and LNR (LN receptor) distributions in Acc-2 and Acc-M cells were studied with immunohistochemical staining.

RESULTS

There were less LN and LNR found in Acc-2, but much more LN and LNR were present in the highly metastatic clone Acc-M. With the presence of exgenous LN, Acc-2 became activated showing a higher migration rate. The cell adhesion test showed that Acc-2 had stronger ability of adhesion than Acc-M with the presence of LN.

CONCLUSION

The result suggests LN and LNR may play a vitral role in the invasion and metastasis of Acc.

Action of pyrroloquinolinequinol as an antioxidant against lipid peroxidation in solution

The activities of pyrroloquinoline quinone (PQQ), a coenzyme of methanol dehydrogenase and amine oxidase, and its reduced form pyrroloquinoline quinol (PQQH2) as an antioxidant have been measured in solution. PQQH2 was stable in the absence of oxygen but rapidly auto-oxidized to PQQ in the presence of oxygen in water. PQQH2 was stable in an aprotic solvent such as acetonitrile, even in air. PQQ did not exert appreciable antioxidant activity, whereas PQQH2 exerted higher reactivity than alpha-tocopherol toward galvinoxyl radical and peroxyl radical. PQQH2 acted as a potent antioxidant against the oxidation of methyl linoleate in acetonitrile induced by azo compound and produced a clear induction period, from which the apparent stoichiometric number was obtained as 1.1. PQQH2 reduced the alpha-tocopheroxyl radical and spared alpha-tocopherol in the oxidation of methyl linoleate. These results suggest that PQQH2 may act as a potent antioxidant, particularly in combination with alpha-tocopherol.

Dynamics of antioxidant action of ubiquinol: a reappraisal

The dynamics of action of ubiquinol as an antioxidant against lipid peroxidation was reinvestigated and compared with that of alpha-tocopherol. It was found that ubiquinol was 2.5 and 1.9 times more reactive than alpha-tocopherol toward phenoxyl and peroxyl radicals, respectively, at 25 degrees C in ethanol and that it was capable of donating two hydrogen atoms toward oxygen radicals but that the apparent stoichiometric number decreased in the inhibition of lipid peroxidation, to even smaller than 1, due to its autoxidation. The autoxidation of ubiquinol proceeded even in the micelles and liposomal membranes in aqueous dispersions as well as in organic homogeneous solution. The apparent antioxidant activity of ubiquinol was smaller than that of alpha-tocopherol against lipid peroxidation in organic solution as judged from either rate of oxidation or duration of inhibition period. They exerted similar antioxidant potency against lipid peroxidation in the membranes and micelles in aqueous dispersions. The combination of ubiquinol and alpha-tocopherol was suggested to be effective.

Effect of modifying metabolic network on poly-3-hydroxybutyrate biosynthesis in recombinant Escherichia coli

The regulatory mechanism for poly-3-hydroxybutyrate (PHB) biosynthesis in recombinant Escherichia coli is markedly different from that of Ralstonia eutropha (formerly, Alcaligenes eutrophus) since the former efficiently synthesizes PHB during growth without any nutrient limitation. To analyze how the central metabolic pathways should be balanced with pathways necessary for cell growth and PHB formation, a stoichiometric model was developed to predict the theoretical maximum PHB production capacity for different metabolic variants. Flux analysis results illustrated the importance of the availability of acetyl-CoA and NADPH for achieving the maximum yield of PHB. In order to examine whether the increased availability of the above substances can enhance PHB synthesis in recombinant E. coli, both genetic and environmental perturbations were attempted. Several E. coli K12 derivatives, namely, HMS174, TA3516 (pta-/ack-), and DF11 (pgi-), were transformed with a plasmid which contains the native phb operon. The fermentation characteristics of these recombinant strains were studied and compared. In this study we examined the effects of intracellular acetyl-CoA accumulation, which may promote PHB synthesis in vivo, by perturbations induced from attenuation of acetate kinase and phosphotransacetylase (TA3516, blocked in the acetate pathway) and by cultivation of E. coli HMS174 on gluconate; it can convert gluconate to acetyl-CoA at a higher rate. The effects of intracellular accumulation of NADPH were investigated by introducing a perturbation induced from attenuation of phosphoglucose isomerase, which redirects the carbon flow to the pentose-phosphate (PP) pathway. Results from the analyses of these perturbations indicate that intracellular buildup of acetyl-CoA may not be able to promote PHB synthesis in vivo. On the other hand, since the biosynthesis of PHB in the pgi- mutant strain can utilize the NADPH overproduced through the PP pathway, the growth of the pgi- mutant on glucose was recovered, indicating that the overproduction of NADPH might be able to enhance PHB synthesis.

Strategies for protein-based nanofabrication: Ni2+-NTA as a chemical mask to control biologically imposed symmetry

BACKGROUND

Technologies that improve control of protein orientation on surfaces or in solution, through designed molecular recognition, will expand the range of proteins that are useful for biosensors, molecular devices and biomaterials. A limitation of some proteins is their biologically imposed symmetry, which results in indistinguishable recognition surfaces. Here, we have explored methods for modifying the symmetry of an oligomeric protein that exhibits useful self-assembly properties.

RESULTS

Escherichia coli glutamine synthetase (GS) contains 24 solvent-exposed histidines on two symmetry-related surfaces. These histidines drive a metal-dependent self-assembly of GS tubes. Immobilization of GS on the affinity resin Ni2+-NTA followed by on-column modification with diethyl pyrocarbonate affords asymmetrically modified GS that self-assembles only to the extent of 'short' dimeric GS tubes, as demonstrated by electron microscopy, dynamic light scattering and atomic force microscopy. The utility of Ni2+-NTA as a chemical mask was also demonstrated for asymmetric modification of engineered cysteines adjacent to the natural histidines.

CONCLUSIONS

Current genetic methods do not provide distinguishable recognition elements on symmetry-related surfaces of biologically assembled proteins. Ni2+-NTA serves as a mask to control chemical modification in vitro of residues within symmetry-related pairs, on proteins containing functional His-tags. This strategy may be extended to modification of a wide range of amino acids with a myriad of reagents.

In vitro selection of RNA molecules that displace cocaine from the membrane-bound nicotinic acetylcholine receptor

The nicotinic acetylcholine receptor (AChR) controls signal transmission between cells in the nervous system. Abused drugs such as cocaine inhibit this receptor. Transient kinetic investigations indicate that inhibitors decrease the channel-opening equilibrium constant [Hess, G. P. & Grewer, C. (1998) Methods Enzymol. 291, 443-473]. Can compounds be found that compete with inhibitors for their binding site but do not change the channel-opening equilibrium? The systematic evolution of RNA ligands by exponential enrichment methodology and the AChR in Torpedo californica electroplax membranes were used to find RNAs that can displace inhibitors from the receptor. The selection of RNA ligands was carried out in two consecutive steps: (i) a gel-shift selection of high-affinity ligands bound to the AChR in the electroplax membrane, and (ii) subsequent use of nitrocellulose filters to which both the membrane-bound receptor and RNAs bind strongly, but from which the desired RNA can be displaced from the receptor by a high-affinity AChR inhibitor, phencyclidine. After nine selection rounds, two classes of RNA molecules that bind to the AChR with nanomolar affinities were isolated and sequenced. Both classes of RNA molecules are displaced by phencyclidine and cocaine from their binding site on the AChR. Class I molecules are potent inhibitors of AChR activity in BC3H1 muscle cells, as determined by using the whole-cell current-recording technique. Class II molecules, although competing with AChR inhibitors, do not affect receptor activity in this assay; such compounds or derivatives may be useful for alleviating the toxicity experienced by millions of addicts.

[Study on pharmacological actions of pingxiaozhitong pill]

Pingxiaozhitong pill was administered ig. once daily for 7 successive days at dosages (4,2,2 g/kg). It was shown markelly suppressive effects on solid sarcoma 180 (S180) and Ehrlich aseites carcinoma (EAC) and synergism effect on cytoxan inhibiting S180 in mice. It had significant analgesic effect. 4,2 g/kg pingxiaozhitong pill enhanced effects on phagocysis of monocyte macrophage and value of hemagglutinin in serum in mice.

[Initial evaluation of mass lesions in the head and neck with enhanced (Gd-DTPA) MR imaging]

OBJECTIVE

To evaluate mass lesions of the head and neck with enhanced (Gd-DTPA) MR imaging.

METHODS

Twenty-five of patients (13 males and 12 females; mean: 46.9 years) suffered from mass lesions of the head and neck inspected with Gd-DTPA MR imaging, 17 cases were certificated histopathologically and followed up. The examinations of all patients were carried out with plain T1-weighted spin-echo sequences (TR/TE = 500-600/30), and Gd-DTPA enhanced T1-weighted spin-echo sequences (TR/TE = 300-500/30).

RESULTS

Comparing with plain MR imaging, 23 mass lesions were stained on SE T1-weighted images (23/25) after intravenous administration of Gd-DTPA. The enhanced patterns of these lesions might be divided into homogeneous (10/23) and inhomogeneous (13/23). Gd-DTPA was helpful in delineating extent of 16 mass lesions.

CONCLUSION

The various morphologic manifestations of enhanced lesions have close relations with their own intimate structures. The enhanced MR imaging is superior to plain MR imaging on displaying the inner structure and extent of diseases and estimating the recurrent lesions.