Expression and cellular location of endothelin-1 mRNA in rat liver following endotoxemia

OBJECTIVE

To study the effect of endotoxin on the alteration of the transcription, expression and cellular location of endothelin-1 (ET-1) mRNA in the hepatic tissue.

METHODS

Wistar rats were divided into control and endotoxic group. The rats in the control group were injected with saline, and those in the endotoxic group with endotoxin at a dose of 10 mg.kg-1 body wt. ET-1 hepatic homogenate was assayed by radioimmunoassay at 3, 6, 9, 12 and 24 h after endotoxin administration. Dot blot was used to identify and quantify ET-1 mRNA of the hepatic tissue. Hybridization of ET-1 of the hepatic tissue was proceeded at 3, 6, 12 and 24 h after endotoxin administration.

RESULTS

ET-1 concentrations and the level of ET-1 mRNA increased rapidly and reached the peak at 6 h, and remained high at 24 h after endotoxin administration. By in situ hybridization, ET-1 mRNA was found in hepatic sinusoids, endothelial cells of portal vein and kupffer cells.

CONCLUSIONS

Endotoxin may be the principal stimulating factor for expression of ET-1 mRNA in hepatic tissue. Endotoxin may affect transcription and translation level of ET-1, leading to increase of the synthesis and release of ET-1. The hepatic vascular endothelial cells, hepatic sinusoids and Kupffer cells all synthesize and release ET-1.

[Efficacy of a triclosan/copolymer dentifrice in the control of plaque and gingivitis: a six-month study in China]

A total of one hundred fifty three healthy male and female adults were entered into a six month, double-blind clinical study designed to evaluate the effect of a dentifrice containing 0.3% triclosan and 2.0% PVM/MA copolymer in a 0.243% sodium fluoride/silica base, relative to a 0.243% sodium fluoride silica base control dentifrice on supragingival plaque accumulation and gingivitis. Plaque and gingivitis were scored after 3 and 6 months' use of the assigned dentifrice. At the end of the study, the dentifrice containing triclosan/copolymer demonstrated an average reduction, relative to the control dentifrice of 16.1% in plaque accumulation and 24.3% in gingivitis. Both were statistically significant(P < 0.001). It was concluded that the twice-daily use of the triclosan/copolymer containing dentifrice resulted in a significant reduction in plaque formation and a significant improvement in gingival health. No side-effects were observed.

Multicenter clinical trial of thrombolytic therapy in 1,406 patients with acute myocardial infarction. Collaborative Group of Clinical Trial for Urokinase Therapy

OBJECTIVE

To investigate the clinical efficacy and safety of intravenous thrombolytic therapy of Urokinase Tech-Pool (UKTP) in acute myocardial infarction (AMI).

METHODS

The data were collected from the 148 participating hospitals from November, 1994 to April, 1996. A total of 1,406 patients with AMI were analyzed to evaluate the clinical efficacy, side effects and mortality of UKTP. The patency of the infarct-related artery (IRA) was evaluated in 124 patients by coronary artery angiography (CAG) 90 minutes after the onset of UKTP infusion.

RESULTS

The reperfusion rate in IRA was 73.5% by clinical standards. The patency rate was 72.6% by CAG. The total mortality during the first 5 weeks was 7.8% (109/1,406). The rate of minor bleeding was 10.2% (143/1,406), of major bleeding 0.43% (6/1,406) and of intracranial hemorrhage 0.50% (7/1,406). In elderly patients (> 75 years old), UKTP was as effective and safe as in younger patients (< 65 years old). Late thrombolytic therapy with UKTP (> 6 hours after the onset of symptom) was still effective. The appropriate dosage of UKTP might be 150 million units of infusion within 30 minutes.

CONCLUSION

UKTP is an effective, reliable and safe agent in the thrombolytic therapy of AMI.

[Clinical study on the antithrombotic effects of Holothuria ldeucospilota acidic mucopolysaccharide]

OBJECTIVE

To study the antithrombotic effects of Holothuria Ldeucospilota Acidic Mucopolysaccharide (HLAM).

METHODS

A series of variables were observed before and after treatment with HLAM in normal middle-aged subjects and patients recovering from cerebral embolism or suffering from ischemic heart disease, each of which were divided into two groups according to the dosage administered (60 mg/d and 120 mg/d).

RESULTS

The fat metabolism was enhanced in addition to the anticoagulant and the blood viscosity reducing effects. No side-effect was found.

CONCLUSION

HLAM is a promising drug for antithrombotic therapy.

Sonic hedgehog participates in craniofacial morphogenesis and is down-regulated by teratogenic doses of retinoic acid

The face is one of the most intricately patterned structures in human and yet little is known of the mechanisms by which the tissues are instructed to grow, fuse, and differentiate. We undertook a study to determine if the craniofacial primordia used the same molecular cues that mediate growth and patterning in other embryonic tissues such as the neural tube and the limb. Here we provide evidence for the presence of organizer-like tissues in the craniofacial primordia. These candidate organizers express the polarizing signal sonic hedghog (shh) and its putative receptor, patched, as well as fibroblast growth factor 8 and bone morphogeneic protein 2. Shh-expressing epithelial grafts functioned as organizing tissues in a limb bud assay system, where they evoked duplications of the digit pattern. High doses of retinoic acid, which are known to truncate the growth of the frontonasal and maxillary processes and thus produce bilateral clefting of the lip and palate, inhibited the expression of shh and patched but not fgf8, in the craniofacial primordia, and abolished polarizing activity of these tissues. From these studies we conclude that the embryonic face contains signaling centers in the epithelium that participate in craniofacial growth and patterning. In addition, we discuss a novel mechanism whereby retinoids can exert a teratogenic effect on craniofacial morphogenesis independent of its effects on Hox gene expression or neural crest cell migration.

Development of vicarious trial-and-error behavior in odor discrimination learning in the rat: relation to hippocampal function?

Previous work from our laboratory has suggested that hippocampal electrolytic lesions result in a deficit in simultaneous, black-white discrimination learning and reduce the frequency of vicarious trial-and-error (VTE) at a choice-point. VTE is a term Tolman used to describe the rat's conflict-like behavior, moving its head from one stimulus to the other at a choice point, and has been proposed as a major nonspatial feature of hippocampal function in both visual and olfactory discrimination learning. Simultaneous odor discrimination and VTE behavior were examined at three different ages. The results were that 16-day-old pups made fewer VTEs and learned much more slowly than 30- and 60-day-olds, a finding in accord with levels of hippocampal maturity in the rat.

Neurologic evaluation of infant and adult rats before and after sciatic nerve blockade

BACKGROUND

Only limited data exist comparing differences in sensory function and responses to neural blockade in infant and adult rats. Therefore, the authors sought (1) to compare baseline thermal, proprioceptive, and postural responses in infant, adolescent, and adult rats; and (2) to compare the effects of sciatic nerve blockade on thermal, proprioceptive, and postural responses in infant, adolescent, and adult rats.

METHODS

Infant, adolescent, and adult rats were evaluated for proprioceptive, thermal, and mechanical nociceptive and motor function before and after sciatic blockade using a detailed neurologic examination.

RESULTS

Mechanical and thermal nociception were present in all rats, starting from age 1 day. The withdrawal reflex latency to pinch was rapid at all ages, whereas that reaction to thermal stimulus depended on both age and temperature. In contrast, the tactile placing response and hopping response were absent at birth and developed completely during the first 10 days of life. The extensor postural thrust was absent in the first 2 weeks of life and developed variably during the first 50 days of life. Sciatic blockade duration is shorter in infant rats than in adult rats receiving the same dose per kilogram. A brief halothane general anesthetic at the time of sciatic injection in infant or adult rats does not alter the duration of blockade.

CONCLUSIONS

Infant rats show increased sensitivity to noxious thermal stimuli and similar response to deep mechanical stimuli compared with adult rats. Their proprioceptive and motor responses develop during the first 2 weeks of life. When doses are scaled by body weight, block duration is shorter in infant than in adult rats.

Catalytic properties and sensitivity to tentoxin of Chlamydomonas reinhardtii ATP synthases changed in codon 83 of atpB by site-directed mutagenesis

The participation of the amino acid beta83 in determining the sensitivity of chloroplast ATP synthases to tentoxin was reported previously. We have changed codon 83 of the Chlamydomonas reinhardtii atpB gene by site-directed mutagenesis to further examine the role of this amino acid in the response of the ATP synthase to tentoxin and in the mechanism of ATP synthesis and hydrolysis. Amino acid beta83 was changed from Glu to Asp (betaE83D) and to Lys (betaE83K), and the highly conserved tetrapeptide betaT82-E83-G84-L85 (DeltaTEGL) was deleted. Mutant strains were produced by particle gun transformation of atpB deletion mutants cw15DeltaatpB and FUD50 with the mutated atpB genes. The transformants containing the betaE83D and betaE83K mutant genes grew well photoautotrophically. The DeltaTEGL transformant did not grow photoautotrophically, and no CF1 subunits were detected by immunostaining of Western blots using CF1 specific antibodies. The rates of ATP synthesis at clamped DeltapH with thylakoids isolated from cw15 and the two mutants, betaE83D and betaE83K, were similar. However, only the phosphorylation activity of the mutant betaE83D was inhibited by tentoxin with 50% inhibition attained at 4 microM. These results confirm that amino acid beta83 is critical in determining the response of ATP synthase to tentoxin. The rates of the latent Mg-ATPase activity of the CF1s isolated from cw15, betaE83D, and betaE83K were similar and could be enhanced by heat, alcohols, and octylglucoside. As in the case of the membrane-bound enzyme, only CF1 from the betaE83D mutant was sensitive to tentoxin. A lower alcohol concentration was required for optimal stimulation of the ATPase of the betaE83K-CF1 than that of CF1 from the other two strains. Moreover, the optimal activity of the betaE83K-CF1 was also lower. These results suggest that introduction of an amino acid with a positively charged side chain in position 83 in the "crown" domain affects the active conformation of the CF1-ATPase.

[Cultivation of intra-pulmonary arteriolar smooth muscle cell from rabbit]

By perfusion with trypsin at low concentration, the intra -pulmonary arterioles were separated carefully and cut into fine tissue pieces. These pieces were then washed with culture medium and used for culture of smooth muscle cells by method of adhesion to wall. Cells cultured were typical smooth muscle cells under light microscope, electron microscope and immunohistochemical test. The method is simple and convenient. It is also applicable to culture of vascular smooth muscle cells from other organs and provides ideal materials for vascular physiopathologic studies.

Effects of 17 beta-estradiol on early afterdepolarizations and L-type Ca2+ currents induced by endothelin-1 in guinea pig papillary muscles and ventricular myocytes

By use of standard microelectrodes and whole cell patch clamp, the effects of 17 beta-estradiol on early afterdepolarizations (EADs) and increase of L-type Ca2+ currents (L-Ica) induced by endothelin-1 (ET-1) were studied in guinea pig ventricular papillary muscles and myocytes. The results indicated that superfusion with ET-1 for 30 min resulted in a marked prolongation of the action potential duration (APD) and caused stable EADs leading to triggered activity occurring at the plateau of the action potentials in isolated guinea pig ventricular papillary muscles. With the addition of 17 beta-estradiol (30 mumol/l), APD was shortened and EADs were decreased. In the patch clamp study, ET-1 induced an increase of mean peak L-Ica from 534.46 +/- 46.23 to 1003.15 +/- 39.12 (pA) with the peak voltage-current curve shifting to the left. When 17 beta-estradiol (30 mumol/l) was added, the L-Ica was decreased by up to 33.32% (p < 0.01) with the peak voltage-current curve shifting to the right. In contrast to the steady-state inactivation curve, ET-1 shifted the steady-state activation curve in the depolarization direction. However, with the addition of 17 beta-estradiol, the deviation of the steady-state activation and inactivation curves caused by ET-1 was suppressed. In conclusion, 17 beta-estradiol appears to attenuate the prolongation of APD and reduce EADs induced by ET-1 in guinea pig papillary muscles by its inhibitory effect on L-Ica.

[A new application of balloon catheter in TAE]

We report a new embolization method with cobra catheter and balloon catheter in TAE for aneurysms and arterioportal fistula. Embolization for one aneurysm and one arterioportal fistula was performed using a cobra catheter, and the target vessel was temporarily blocked using a balloon catheter during the intervention. 2 cases of aneurysms and arterioportal fistula were treated successfully without coils reflux. Application of both cobra catheter with balloon catheter in TAE is effective without complication.

A comparative study of intravenous accelerated streptokinase dose regimen with conventional dose regimen for coronary thrombolysis

The aim of this study is to test the patency rate and safety of the accelerated streptokinase dose regimen for coronary thrombolysis compared with the conventional one. One hundred and four patients entering three hospitals up to 12 hours after the onset of definite acute myocardial infarction were randomizely treated with intravenous accelerated streptokinase dose regimen (1.5 million units/30 min) (group A, 47 cases) and conventional dose regimen (1.5 million units/60 min) (group B, 57 casese). The reperfusion rate of infarct-related arteries determined by clinical evidence of reperfusion was 76.6% (36/47) in group A VS 61.4% (35/57) in group B. There was significant difference in reperfusion rates among patients within 6 hours after the onset of chest pain: 87.9% (29/33) in group A VS 67.4 (29/43) in group B (P < 0.05). The incidence of mild bleeding, allergic reaction, hypotension was 12.8% (6/47), 4.3% (2/47), 12.8 (6/47) respectively in group A vs 21.1 (12/57), 3.5 (2/57), 17.5% (10/57) respectively in group B. Compared to conventional dose regimen, intravenous accelerated streptokinase dose regimen for coronary thrombolysis seems to improve reperfusion rate markedly without increasing adverse events such as bleeding, allergic reaction and hypotension. It suggests that accelerated streptokinase therapy deserves more extensive investigation.

Mouse lethal activity of a HEp-2 vacuolation factor, cereulide, produced by Bacillus cereus isolated from vomiting-type food poisoning

The HEp-2 vacuolation factor (or cereulide) produced by Bacillus cereus isolated from vomiting-type food poisoning, which is supposed to induce emesis, was found to give mouse and suncus lethality after intravenous and intraperitoneal administration. The emetic activity of the factor was also found to be resistant to heating at 121 degrees C for 15 min, exposure to pH 2 and 11, and to digestion with proteolytic enzymes such as pepsin and trypsin. These findings suggest that the cereulide produced by B. cereus is stable in the digestive tracts, induce emesis, and show lethal activity leading to cellular damage.

Changes in substance P in the jejuna of rats after burns

Radioimmunoassay (RIA) was used to determine the dynamic changes of immunoreactive substance P (iSP) in the jejuna of rats (TBSA 30 per cent full skin thickness burn) during the first 72 h postburn. Immunohistochemistry and image analysis techniques were used to observe and quantitate the SP immunoreactivity (SP-IR) of positive nerve fibres in the villi of jejuna postburn. Changes in the amount of iSP in jejuna of burned rats were: (1) iSP increased significantly at 1 h postburn, and the high level of iSP lasted 4 h; it then decreased greatly 8 h later with the low level of iSP persisting for 72 h. (2) Significant changes in SP-IR-positive nerve fibres in the villi after burn were shown by the immunohistochemical studies including the morphoses; the distributive densities and SP-IR-positive products in the SP-IR-positive nerve fibres. The results quantified by image analysis showed similar alterations in the distributive densities and SP-IR-positive products in the nerve fibres in the villi during 72 h postburn; which were distinctly elevated by 1 hr then dropped by 8 h and 12 h and finally elevated again. The results indicated that the irritation-release and consumption of SP occurred in jejuna of rats after burns. It might be that SP contributed to the postburn intestinal lesion in rats by bioactivities, such as enhancing the vascular permeability and regulating the intestinal movement. The SP peptidergic nerve fibres of the villus had a direct effect on the damage to mucosal epithelia.

[A review of 10 patients of nephrectomy through laparoscope video]

Ten patients were subjected to nephrectomy through laparoscope video. Compared with routine nephrectomy, it has such merits as slight trauma, less bleeding and pain during the operation as well as quick recovery and short hospitalization. In 6 male patients and 4 female patients the oldest one was 75 years old, and the youngest one was 15 years old. Seven patients suffered from nephrohydrosis and 3 from polycystic kidney. Before the operation, the patients were found the loss of function of the diseased kidney. The video scope was inserted into the abdominal cavity through an operating hole under the navel making the exploration in the cavity; the other operations are as basical as routine operations. The ill kidney was cut off and put into a special pocket, then it was cut into pieces, and taken out. The abdominal membrane was enclosed by the emanometer, the drainage tube kept. In the 10 patients the operations were successful and satisfactory.

[Arterioportal fistulas in the extra-hepatic circulation of the common hepatic artery. Diagnosis and radiologic interventional therapy]

Two cases of arterioportal fistulas and new possibilities in diagnosis and treatment are reported: A 62-year-old women was admitted to our hospital with abdominal pain. Color flow duplex sonography showed an arterioportal fistula between the proper hepatic artery and the ectatic portal vein that was confirmed by angiography, permitting percutaneous embolization as a definitive treatment. The pain disappeared immediately. A 36-year-old man underwent surgery due to a penetrating gastric ulcer. He was referred to us with an abdominal murmur. Color flow duplex sonography proved by spiral CT with 3D reconstruction and maximum intensity projection (angio-CT) revealed an arteriovenous fistula between the gastroduodenal artery and a mesenteric branch. Angiography confirmed the diagnosis and permitted definitive therapeutic embolization.

[Observation and analysis of postburn changes in substance P (SP) and SP peptidergic nerve fibers in the intestine of rat]

Substance P (SP) was measured by radioimmunoassay (RIA) and SP peptidergic nerve fibers were identified by Immunohistochemistry (IHC) in the intestinal wall of rats (TBSA 30% and with full-thickness burn) during 72 hours after burn. The results were as follows: (1) SP increased significantly at 1 hr and 4 hr postburn, then decreased markedly 8 hr later, and the low was maintained up to 72 hr. (2) The significant changes in SP peptidergic nerve fibers in the villi after burn were found with immunohistochemical studies including the morphology, distributive densities and SP contents of the SP peptidergic nerve fibers. The results from image analysis showed that the distributive densities of the nerve fibers elevated distinctly in 1 hr group, then dropped at 8 hr and 12 hr and finally elevated again. The results indicated that, the SP release might occur leading to SP consumption in the intestinal wall of rats after burn. It is possible that SP contributes to the postburn intestinal lesion in rats. The SP peptidergic nerve fibers in villus have a direct effect on the damage of intestinal mucosal barrier.

[Response and mechanism of vasovagal syncope induced by tilt table test]

Tilt table test (TTT) is done in 110 cases of unexplained syncope and 37 healthy controls. As a result, there is no significant difference in basal diastolic blood pressure (DBP), basal heart rate (HR) x DBP among TTT positive, TTT negative and healthy controls; but DBP and HR x DBP of TTT positive patients at the instant of syncope is not significantly different from their basal values, the HR at the instant of syncopy statistically in not different from the basal HR. These data suggest that not the same mechanism is responsible for the changes of BP and HR. In seventy percent of the TTT positive patients vasovagal syncope (VS) may be provoked by isoproterenol. So the occurrence of VS may be related to hypersensitivity of beta-receptor. TTT may be an approach to unravel the pathogenesis of VS.

[Effect of dl-3-n-butylphthalide (NBP) on purine metabolites in striatum extracellular fluid in four-vessel occlusion rats]

The effects of NBP on concentrations of some purine metabolites in extracellular fluid of rat striatum during global ischemia and reperfusion were studied. Global ischemia was produced by the four-vessel occlusion method. Push-pull cannula was implanted stereotaxically into the striatum of rat and was perfused with Ringer's solution at a flow rate of 2.5 microliters.min-1. The level of adenosine(Ade), inosine(Ino), hypoxanthine(Hyp) and xanthine(Xan) in perfusates were measured with HPLC connected with a UV detector. The results indicate that the levels of ade, ino, hyp and xan were significantly increased (about 3-5 times of initial value) during cerebral ischemia and reperfusion. NBP at the dose of 20 or 40 mg.kg-1 given intra-peritoneally 20 min before ischemia was shown to depress the increase of ade, ino, hyp and xan during ischemia and reperfusion dose dependently. But no change in the level of purine metabolites was found in sham operated rats. It has been known that harmful free radicals were produced when xan and uric acid were formed by xanthine oxidase during reperfusion. This might be important for the development of ischemic injuries. Our findings suggest that the effect of NBP might be beneficial for protection against post-ischemic neuronal damage.

[Effect of dl-3-butylphthalide on the striatum extracellular amino acid and dopamine contents in the rat during cerebral ischemia]

The effect of dl-3-butylphthalide (NBP) on the contents of amino acids and dopamine in the rat striatum during globe cerebral ischemia has been studied. By using the technique of microperfusion in the striatum of rats subjected to 4-vessel occlusion cerebral ischemia, the extracellular contents of glutamate, taurine, gamma-aminobutyric acid and dopamine were found to be significantly increased in the striatum during the 20 min of cerebral ischemia. NBP (40 mg.kg-1; i.p. 30 min before ischemia) was shown to reduce the contents of dopamine and its metabolite, 3,4-dihydroxyphenylacetic acid (DOPAC), in the striatal extracellular fluid of the rat during ischemia. The content of glycine before and after ischemia was also reduced. However, no significant effect on the contents of glutamate and some other amino acids was observed. The results suggest that NBP may improve the striatal ischemic injury.

Transseptal methods for percutaneous balloon valvoplasty simultaneously with radiofrequency catheter ablation

Percutaneous balloon mitral valvoplasty (PBMV) and radiofrequency catheter ablation (RFCA) have been used in the treatment of mitral stenosis (MS) and supraventricular tachycardia. The techniques of PBMV and RFCA yield better results with the development of interventional cardiology, but there is no report about PBMV performed simultaneously with RFCA in the same patient. Seven patients with mitral stenosis and Wollf-Parkinson-White (W-P-W) Syndrome were successfully treated with PBMV and RFCA by transseptal methods. LA, LAP, mPG and mPA were decreased from 43.4 +/- 4.6mm, 21.8 +/- 6.8mmHg, 21 +/- 7.7mmHg and 45.7 +/- 16.5mmHg to 39.2 +/- 3.7mm (P < 0.05), 12.7 +/- 4.5mmHg, 12 +/- 3.7mmHg and 32.3 +/- 9mmHg (P < 0.01). MVA was increased from 0.96 +/- 0.33cm2 to 1.7 +/- 0.80cm2 (P < 0.01). delta wave disappeared in 12-lead surface EKG and SVT could not be induced in electrophysiological study after the treatment. The overall time of the procedure for this series was 93 +/- 34 minutes and fluoroscopy time was 23 +/- 7 minutes on the average. Radiofrequency energy applications were 3 +/- 2 times each procedure. PBMV and RFCA are safe and highly effective in the treatment of MS and W-P-W syndrome. The results in the present study proved the feasibility of the combined use of PBMV and RFCA. We prefer a first choice of PBMV and then RFCA in order to avoid aggravation of the hemodynamics due to mitral stenosis. The results also showed that of overall procedure and fluoroscopy only took a short time for this series. We suggest that it could be used as a routine method for the treatment of mitral stenosis complicated by W-P-W syndrome.

[Scavenging effects of daphnetin and its Cu, Zn complexes on superoxide radical]

The scavenging effects of daphnetin (D) and its Cu, Zn complexes on superoxide radical (O2-.) generated through the photooxidation of riboflavin were studied with human red blood cells (RBC) and RBC membrane as experimental material. The Cu ( II ) complex showed the highest activity. SOD, D and its Cu ( II ), Zn ( II ) complexes were found to have inhibitory effect on the production of lipid peroxide in the membrane, SOD being the best among them.

Flow cytometric assay for cytotoxic activity of crude Clostridium perfringens enterotoxin using non-adherent cell FM3A

The flow cytometric assay method was tested for the cytotoxic activity of Clostridium perfringens enterotoxin (CPE) in culture using mouse mammary carcinoma cell line FM3A stained with propidium iodide (PI). From the results obtained, FM3A cells proved to be susceptible to CPE. A reproducible dose-response curve with FM3A was obtained between crude CPE at 13.9-109 ng/ml and between purified CPE at 40-400 ng/ml, respectively. These findings indicate that non-adherent FM3A is preferable to determine the cytotoxic activity of CPE because it can be used without detachment procedures with trypsinin compared with adherent African monkey kidney cell line (Vero cells). Furthermore, the flow cytometry with non-adherent cell FM3A stained with PI only proved to be a useful method to determine the biological activity of CPE in culture isolates.

[Predictive values for slow pathway modification of atrioventricular nodal reentrant tachycardia]

The predictive values of various ECG parameters for slow pathway modification were studied in 42 slow-fast AVNRT patients. The negative predictive values of a stable ECG, junctional rhythm, and slow pathway potential were as high as 94.8%, 94.9% and 84.9% respectively. But, their positive values were 29.4%, 15.1% and 23.9%. The possibility of success (PS) raised with increasing of width and peak number of A wave. When the width of A wave was > or = 80ms, PS was 50%. When the peak number of A wave was > 7, PS was 80%. A/V ratio varied from 0.14 to 1 in 93.2% of successful sites. When A/V ratio was 0.25, PS reached its peak value of 33.3%.

A simple test of the vicarious trial-and-error hypothesis of hippocampal function

Vicarious trial-and-error (VTE) is a term that Muenzinger and Tolman used to describe the rat's conflict-like behavior before responding to choice. Recently, VTE was proposed as a mechanism alternative to the concept of "cognitive map" in accounts of hippocampal function. That is, many phenomena of impaired learning and memory related to hippocampal interventions may be explained by behavioral first principles: reduced conflicting, incipient, pre-choice tendencies to approach and avoid. The nonspatial black-white discrimination learning and VTE behavior of the rat were investigated. Hippocampal-lesioned and sham-lesioned animals were trained for 25 days (20 trials per day) starting at 60 days of age. Each movement of the head from one discriminative stimulus to the other was counted as a VTE instance. Lesioned rats had fewer VTEs than sham controls, and the former learned much more slowly or never learned. After learning, VTE frequency declined. Male and female rats showed no significant differences in VTE behavior or discrimination learning.

[Effects of interferon treatment on mutation of hepatitis B virus precore genome]

Effects of interferon (IFN) treatment on mutation of hepatitis B virus (HBV) precore were studied with a rapid polymerase chain reaction method to investigate the stop codon in the distal precore region during HBV precore mutation. 6 cases of chronic hepatitis B were treated with recombinant IFN alpha 1 3 x 10(6) U/day for 14 weeks. In 4 of them HBV DNA was undetectable after treatment. Precore mutant was detected in the remaining 2 cases whose HBV DNA was still positive. In a group of 11 cases not treated with IFN, mutants were detected in 3. HBV e antigen (HBeAg) became negative after IFN treatment in one case, the original wild strain was replaced by a status of co-existence of mutant and wild strain. These results suggest that HBeAg negative seroconversion after IFN treatment does not necessarily implicate a complete clearance of HBV and the possibility of mutation of precore still exists.

Interactions of human nuclear proteins P1Mcm3 and P1Cdc46

Human nuclear proteins P1Mcm3 and P1Cdc46 have high sequence similarities with the corresponding yeast proteins known to be required for the initiation of genome replication. Nuclei of proliferating HeLa cells contain relatively high amounts of P1Mcm3 (about 10(6) molecules/nucleus) of which only a small fraction is bound to a nuclear structure, most probably chromatin. At 0.5 M NaCl, the structure-bound nuclear protein can be partially solubilized as a dimer composed of P1Mcm3 and the related protein P1Cdc46. However, most protein P1Mcm3 is not bound to a nuclear structure and appears in the nucleoplasm. About 10% of protein P1Mcm3 in the soluble fraction is free and uncomplexed, and the remaining P1Mcm3 forms stable complexes with protein P1Cdc46. These P1Mcm3/Cdc46 complexes occur as dimers and in high-molecular-mass complexes (approximately 500 kDa). The high-molecular-mass complexes dissociate in 0.5 M NaCl and release P1Mcm3/Cdc46 dimers. It has frequently been proposed that the Mcm proteins may function as licensing factors for genome replication. Our data imply that the active form of an Mcm protein is not a monomer, but a protein complex that includes an Mcm3/Cdc46 dimer. DNA polymerase alpha is not a component of this complex.

Building synthetic antibodies as adhesive ligands for integrins

An antibody engineering strategy was employed to build high affinity ligands and antagonists of integrins alpha v beta 3 and alpha IIb beta 3. Previously, we inserted the integrin recognition motif, RGD, into the antigen binding site of a human antibody and selected the optimal flanking sequences from a phage-display library (Barbas, C. F., Languino, L. R., and Smith, J. W. (1993) Proc. Natl. Acad. Sci. U.S.A. 90, 10003-10007). The resulting antibody, Fab-9, blocked the function of integrin alpha v beta 3 but also bound to the ligand binding site of platelet integrin alpha IIb beta 3. In this report, the antibody engineering effort has been extended by 1) redesigning Fab-9 to achieve specificity for platelet integrin alpha IIb beta 3, 2) building non-RGD-containing antibodies that bind the ligand binding site of both beta 3-integrins, and 3) testing the hypothesis that peptides derived from complementarity determining regions (CDR) can be used to emulate the activity of the parent synthetic antibody. These goals were accomplished by subjecting the original antibody, Fab-9, to a "motif optimization" (MTF). A phage library was constructed in which the residues flanking the RGD motif in Fab-9 were maintained, but the RGDX sequence was randomized. This library was panned on purified alpha IIb beta 3 to identify high affinity binders. Four function-blocking antibodies lacking RGD, but with specificity for alpha IIb beta 3, were characterized. The antibody with the highest preference for alpha IIb beta 3, MTF-10, had an adhesion sequence of KGDN. This sequence is similar in primary structure to the active sequence within the disintegrin barbourin, which also antagonizes alpha IIb beta 3 (Scarborough, R. M., Rose, J. W., Hsu, M. A., Phillips, D. R., Fried, V. A., Campbell, A. M., Nannizzi, L., and Charo, I. F. (1991) J. Biol. Chem. 266, 9359-9362). MTF-10 had a 70-fold higher affinity for alpha IIb beta 3 than alpha v beta 3. Through our selection strategy, we also identified several antibodies that lack RGD but still blocked ligand binding to both integrins with high affinity. Therefore, the RGD sequence is not necessary for a high affinity interaction with the ligand binding site of beta 3-integrins. Further investigation showed that the activity of inhibitory antibodies could be emulated by synthetic peptides derived from the protein sequences of the antibody's HCDR3. CDR-derived peptides blocked ligand binding to integrins and maintained essentially the same specificity as the parent antibody.

Sensitivity of United States HIV antibody tests for detection of HIV-1 group O infections

Infections by highly divergent strains of HIV-1, first detected in central Africa and grouped provisionally as group O, have not been reliably detected by certain European HIV screening tests. Serum specimens from eight probable group O infections from Cameroon were tested by ten HIV assays licensed by the US Food and Drug Administration. All assays based on synthetic peptides or recombinant antigens failed to detect at least one of the infections; assays based on whole-virus lysates performed better. Divergent HIV strains may be undetected by current HIV tests. Thus active surveillance for and characterisation of HIV variants to evaluate and, when necessary, modify current tests is urgently needed.

Postlicensure effectiveness of the Haemophilus influenzae type b polysaccharide-Neisseria meningitidis outer-membrane protein complex conjugate vaccine among Navajo children

The incidence of invasive Haemophilus influenzae type b (Hib) infection was decreased significantly among Navajo children since the licensure of Hib conjugate vaccines, even though two lots of Hib (polyribosylribitol phosphate)-meningococcal B outer-membrane protein conjugate vaccine (PRP-OMP) widely used among the Navajo were later found to be of low immunogenicity. We measured the effectiveness of all Hib conjugate vaccines combined, PRP-OMP alone, and the PRP-OMP lots with lower-than-expected immunogenicity among Navajo infants and children. This was a matched case-control study using active, laboratory-based surveillance for the ascertainment of Navajo children 2 1/2 to 59 months of age with invasive Hib infection; 45 patients with infection and 180 control subjects were enrolled. The effectiveness of one, two, and three doses, respectively, of all Hib conjugate vaccines combined was 96% (95% confidence interval (CI) 65%, 99%), 99% (95% CI, 69%, 100%), and 99% (95% CI - 57%, 100%). The effectiveness of one or more doses of PRP-OMP was 95% (95% CI, 66%, 99%). The effectiveness of a single dose of the lots of lower-than-expected immunogenicity was 89% (95% CI, -8%, 99%). The Hib conjugate vaccine coverage increased from 49% during 1991 to 94% during 1992; no control subjects younger than 18 months of age were enrolled during 1993. The occurrence of invasive Hib infections in this population after licensure of Hib conjugate vaccines was the result of gradual vaccine uptake, not poor vaccine effectiveness. The use of PRP-OMP has been highly effective despite concerns about the immunogenicity of several lots.

Predictors of early and late recurrence of atrioventricular accessory pathway conduction after apparently successful radiofrequency catheter ablation

The correlation between electrophysiologic parameters and recurrence in 239 patients who underwent successful catheter ablation for an accessory pathway mediated tachycardia was analysed. Pathway conduction recurred in 15 patients (6.3%) after a mean follow-up of 7.3 months. Recurrence was most common in patients with right free wall pathways (17.1%). Accessory pathway conduction resumed in 18.9% of patients with decremental ventriculo-atrial (VA) conduction post-ablation compared with those patients without VA conduction (3.4%) (P < 0.001). Recurrence was common also in patients with repeated return of accessory pathway conduction during the ablation procedure (40% vs. 1.3%, P < 0.01). The patients in whom these observations are made should be monitored closely for recurrence of accessory pathway conduction post-ablation.

Epidural analgesia in labor and cesarean delivery for dystocia

Published studies assessing the effect of epidural analgesia in nulliparous labor on the frequency of cesarean delivery for dystocia are reviewed. There are at least four retrospective studies and two prospective studies that suggest that epidural analgesia may increase the risk of cesarean delivery for dystocia in first labors. The potential for epidural to increase the frequency of cesarean delivery for dystocia is likely influenced by multiple variables including parity, cervical dilatation at epidural placement, technique of epidural placement, management of epidural during labor, and the obstetrical management of labor after placement of epidural analgesia. Two studies suggest that delaying placement of the epidural until 5 cm of cervical dilatation or greater may reduce the risk of cesarean birth. Epidural is safe and may be a superior labor analgesic when compared with narcotics. However, patients should be informed that epidural analgesia may increase the risk of cesarean birth in first labors.

In vitro evolution of a neutralizing human antibody to human immunodeficiency virus type 1 to enhance affinity and broaden strain cross-reactivity

A method is described that allows for the improvement of antibody affinity. This method, termed complementary-determining region (CDR) walking, does not require structural information on either antibody or antigen. Complementary-determining regions are targeted for random mutagenesis followed by selection for fitness, in this case increased binding affinity, by the phage-display approach. The current study targets a human CD4-binding-site anti-gp120 antibody that is potently and broadly neutralizing. Evolution of affinity of this antibody demonstrates in this case that affinity can be increased while reactivity to variants of human immunodeficiency virus type 1 is broadened. The neutralizing ability of this antibody is improved, as assayed with laboratory and primary clinical isolates of human immunodeficiency virus type 1. The ability to produce human antibodies of exceptional affinity and broad neutralizing ability has implications for the therapeutic and prophylactic application of antibodies for human immunodeficiency virus type 1 infection.

[A community cohort study on risk factors of strokes in Shanghai: a Cox regression analysis on 15,885 subjects]

Baseline investigation on 15,885 subjects who were over thirty-five years old had been launched since July 1987. All of them were selected from eighteen neighbourhoods of three districts in Shanghai by using multiple stage cluster sampling procedure. All of them were followed up till the end of 1989. Each new case of stroke was randomly matched with about twenty controls by age and sex. The total 2,682 controls together with 127 new cases of strokes were analyzed by using Cox regression model for risk factors. The population attributable risk proportion (PARP) of factors was also estimated.

Retrograde conduction properties after catheter radiofrequency ablation of atrioventricular accessory pathways

A total of 208 atrioventricular (AV) accessory pathways in 200 patients were abolished by catheter radiofrequency current ablation. The antegrade AV conduction was normal after the ablation. Approximately 66% of the patients experienced retrograde AV conduction dissociation, which is independent of the age, gender and antegrade conduction properties of accessory pathways (manifest or concealed). Retrograde conduction dissociation is more prevalent than decremental conduction in patients with left free (80% vs. 17%, P < 0.001) or right free (78.6% vs. 21.4%, P < 0.01) wall pathways. Eleven patients (5.5%) showed recurrence after an average of 213 days follow-up. The recurrence of right free wall pathways (21.4%) is much more common than that of left free wall (2.5%) and posteroseptal (4.8%) pathways. The recurrence in those with decremental conduction after the initial successful ablation is higher than that of patients with retrograde AV dissociation (8.8% vs. 3.8%, P < 0.01), and most of them required a second ablation session.

CONCLUSION

most of the patients, especially those with free wall accessory pathways, will have retrograde conduction dissociation after the successful radiofrequency catheter ablation. Electrophysiological studies should be carefully performed on patients with decremental retrograde conduction after the ablation.