Effect of dissolved CO2 on the potential stability of all-solid-state ion-selective electrodes

The influence of dissolved CO2 on the potentiometric responses of all-solid-state ion-selective electrodes (ISEs) was systematically examined with four different types of electrodes fabricated by pairing pH-sensitive and pH-insensitive metal electrodes (Pt and Ag/AgCl, respectively) with pH-sensitive and pH-insensitive ion-selective membranes (H+-selective membrane based on tridodecylamine and Na+-selective membrane based on tetraethyl calix[4]arenetetraacetate, respectively). The experimental results clearly showed that the carbonic acid formed by the diffused CO2 and water vapor at the membrane/metal electrode interface varies the phase boundary potentials both at the inner side of the H+-selective membrane (deltaE(in)mem) and at the metal electrode surface (deltaEelec). The potential changes, deltaE(in)mem and deltaEelec, occurring at the facing boundaries, are opposite in their sign and result in a canceling effect if both the membrane and metal surface are pH-sensitive. Consequently, the H+-selective membrane coated on a pH-sensitive electrode (Pt) tends to exhibit a smaller CO2 interference than that on a pH-insensitive electrode (Ag/AgCl). When the all-solid-state Na+ and K+ ISEs were fabricated with both pH-insensitive metal electrode and ion-selective membrane, they did not suffer from CO2 interference. It was also confirmed that plasticization of the PVC leads to increased CO2 permeation. Various types of intermediate layers were examined to reduce the CO2 interference problem in the fabrication of H+-selective all-solid-state ISEs. The results indicated that the H+-selective electrode needs an intermediate layer that maintains a constant pH unless the carbonic acid formation at the interfacial area is effectively quenched.

PACAP stimulates gastric acid secretion in the rat by inducing histamine release

Previous studies have shown that pituitary adenylate cyclase-activating peptide (PACAP) stimulates enterochromaffin-like (ECL) cell histamine release, but its role in the regulation of gastric acid secretion is disputed. This work examines the effect of PACAP-38 on aminopyrine uptake in enriched rat parietal cells and on histamine release and acid secretion in the isolated vascularly perfused rat stomach and the role of PACAP in vagally (2-deoxyglucose) stimulated acid secretion in the awake rat. PACAP has no direct effect on the isolated parietal cell as assessed by aminopyrine uptake. PACAP induces a concentration-dependent histamine release and acid secretion in the isolated stomach, and its effect on histamine release is additive to gastrin. The histamine H2 antagonist ranitidine potently inhibits PACAP-stimulated acid secretion without affecting histamine release. Vagally stimulated acid secretion is partially inhibited by a PACAP antagonist. The results from the present study strongly suggest that PACAP plays an important role in the neurohumoral regulation of gastric acid secretion. Its effect seems to be mediated by the release of ECL cell histamine.

Efficiency, efficacy, and adverse effects of adenovirus vs. liposome-mediated gene therapy in cardiac allografts

Virus- and nonvirus-mediated immunosuppressive cytokine gene therapy prolongs cardiac allograft survival in various nonfunctional heart transplant animal models, but its cardiac adverse effects have not been addressed. Recently, we developed a functional heterotopic heart transplant model in rabbits. For the first time, we were able to systematically compare the efficiency, efficacy, and adverse effects of optimized adenovirus- and liposome-mediated ex vivo interleukin (IL)-10 gene transfer in functional donor hearts. The efficiency of liposome-mediated gene transfer was greatly improved in physiologically functioning donor hearts and was only three- to fourfold lower than adenovirus-mediated gene transfer. The efficacy of liposome-mediated IL-10 gene transfer was much higher than that mediated by adenovirus. Significant negative inotropic and arrhythmogenic adverse effects on transplanted hearts were observed due to viral cytotoxicity and immunogenesis, which greatly abated the therapeutic efficacy of this first generation adenovirus-mediated gene therapy.

Increased incidence of atrial flutter associated with the rejection of heart transplantation

Atrial fibrillation (AF) and atrial flutter (Afl) are common dysrhythmias that occur after orthotopic heart transplantation (OHT); however, their etiology and clinical significance have not been defined. To determine the precise incidence of sustained AF and Afl and their association with cardiac rejection, 892 consecutive patients who underwent OHT were studied. A total of 104 patients had 113 episodes of Afl; 102 patients had 117 episodes of AF. The incidence of Afl (12.7%) was the same as AF (13.1%). Sixty-nine AF episodes occurred in first 2 weeks after transplantation, and 22 of which were associated with rejection. In contrast, only 20 Afl episodes occurred the first 2 weeks after OHT, 10 of which were associated with rejection. Fifty-two episodes of Afl occurred during from the third week to 6 months after transplantation, 34 of which were associated with moderate to severe cellular or humoral rejection and/or transplant coronary artery disease (TCAD). All 41 Afl episodes that occurred 6 months after transplantation were associated with cellular and humoral rejection, and/or TCAD. The prevalence of Afl was significantly higher in biatrial than bicaval anastomosis. Atrial conduction defect, manifested by the increase of terminal force of the P wave in lead V(1) of the surface electrocardiogram, predicted the occurrence of Afl and AF associated with rejection in OHT with a sensitivity of 89% and specificity of 92%. These results demonstrate that the incidence of Afl increased after OHT, which might be a consequence of cellular and humoral rejection, and coronary vasculopathy of the transplanted hearts.

Effect of pre-treatment on the surface and electrochemical properties of screen-printed carbon paste electrodes

The effect of various electrochemical pre-treatment methods on the surface and electrochemical properties of screen-printed carbon paste electrodes (SPCE) prepared with three different commercial products was examined. It was observed that a positively charged redox couple, e.g., hexaammineruthenium(III), exhibited quasi-reversible behavior at the untreated SPCE. However, the cyclic voltammograms (CVs) of the SPCE prepared with general-purpose carbon inks did not exhibit clear redox peaks to other representative redox couples [e.g., hexacyanoferrate(III), hexachloroiridate(IV), dopamine, and hydroquinone] without activation. Electrochemical pre-treatment methods were sought in four different aqueous solutions, i.e., sulfuric acid, potassium chloride, sodium hydrogencarbonate, and sodium carbonate, applying various activation potentials. It was found that the pre-treatment procedure in saturated Na2CO3 solution at 1.2 V provides a mild and effective condition for activating the SPCE. By measuring the water contact angles at the SPCE surfaces and recording their SEM images, it was confirmed that the electrochemical pre-treatment effectively removes the organic binders from the surface carbon particles. A prolonged period of activation (> 5 min) or the use of high potentials (> 1.2 V) increased the capacitance of the electrode over 20 microF cm(-2). The pre-treated SPCE behaved like a random array microelectrode, exhibiting a sigmoidal-shaped CV at a slow scan rate. The short pre-anodization method in Na2CO3 solution was generally applicable to most SPCE prepared with general-purpose carbon inks.

Cartilage-like phenomenon in the anterior cruciate ligamenta

OBJECTIVE

To detect histological characteristic of anterior cruciate ligament (ACL) and medial collateral ligament (MCL).

METHODS

In each of 20 skeletally mature male mongrels and 4 men, the ACL and MCL were examined by standard hematoxylin-eosin procedure and toluidine blue staining for histologic observation.

RESULTS

The fibroblasts in medial collateral are elongated to spindle shape and aligned in a row between the bundles of collagenous fibers. Toluidine blue staining is negative. The anterior cruciate ligament demonstrated more heterogenous cell types and arrangement. It had three major cell forms: spindle, round and ovoid type, which were shorter but greater than the cells in medial collateral ligament. Toluidine blue staining was positive in anterior cruciate ligament. Most cells in anterior cruciate ligament were enclosed within lacunae.

CONCLUSION

This study suggests that the ACL has different histological characteristics from MCL, and is more cartilage-like in nature.

Effects of human tissue plasminogen gene transfer on allograft coronary atherosclerosis

BACKGROUND

Transplant coronary atherosclerosis is a major limiting factor to successful long-term cardiac transplantation. The depletion of tissue plasminogen activator (tPA) in the arteriolar smooth muscle cells has been associated with a higher incidence of accelerated graft atherosclerosis. In vivo overexpression of tPA may inhibit accelerated graft atherosclerosis and improve the long-term results of heart transplantation. We evaluated the feasibility, distribution, and effects of intracoronary transfer of the human tPA (htPA) gene in a rabbit heterotopic cardiac transplant model, using a novel cationic liposome compound designed for improved delivery to vascular endothelium.

METHODS

Human tPA cDNA under the control of the SV40 promoter (100 microg) was complexed with the novel cationic liposome (+/-)-N-(3-aminopropyl)-N,N-dimethyl-2,3-bis(dodecyloxy)-1-propanaminium bromide (GAP: DLRIE) (50 microg), and delivered ex vivo to the donor heart by slow intracoronary infusion. Control hearts received an "empty" liposome preparation. Grafts were then implanted into recipient rabbits in the heterotopic cervical position. For the analysis of gene expression, beating donor hearts were collected at 4 days. To examine the effects of htPA expression on graft atherosclerosis, animals received a 0.5% cholesterol diet for 30 days posttransplant, as well as 10 mg/kg cyclosporine A daily. Beating hearts were collected at 30 days posttransplant and analyzed for the development of transplant atherosclerosis by image analysis.

RESULTS

Northern blot analysis for the htPA messenger RNA (mRNA) transcripts showed significantly higher counts in hearts receiving the htPA gene as compared to controls. The distribution of these transcripts favored the left ventricle (LV) and septal regions over the right ventricle (RV). Scintillation analysis of specimens stained by immunoflourescence showed expression of htPA throughout the perivascular myocardium that was significantly higher in grafts transduced with the htPA gene than in control or native hearts. Expression in the vascular wall was also significantly enhanced. Scintillation counts per x 200 field were 262 +/- 145 in htPA-transduced hearts and 20 +/- 27 in controls (p = 0.001), and mean luminescence was 83.7 +/- 12.5 in htPA-transduced hearts and 62.9 +/- 12.8 in controls (p = 0.01). Intimal hyperplasia was assessed by mean percent luminal stenosis in small- and medium-sized arteries and was 31.12 +/- 23.5% in htPA-transduced hearts and 86.59 +/- 17.5% in control hearts (p < 0.0001). These results demonstrate that expression of the htPA gene can be induced by ex vivo intracoronary gene transfer at the time of allograft preservation. Liposome-mediated delivery of the htPA gene at the time of transplantation results in significant early transgene expression, and significantly inhibits the development of graft coronary atherosclerosis.

[Modeling research about bioremediation of organic pollutants in soil-water-microbes system]

A new Theory, organic pollutant sequestration inside soil particles, was applied in the research in order to explain the persistence of residual chemicals in remediation sites. Based on this theory, a mathematical model which simulates organic pollutant bioremediation process in soil-water-microbes system was developed. In the model, diffusion is represented by Fick's second law, reversible sorption-desorption by a linear isotherm, irreversible sequestration by a pseudo-first order kinetics, and biodegradation by Monod kinetics. Model results match successfully with experimental data. Model simulations are performed in the study. It is noteworthy that the mathematical model will be useful in quantitatively predicting the time and degradation extend of organic pollutant in remediation sites.

Differences in mechanisms of SR dysfunction in ischemic vs. idiopathic dilated cardiomyopathy

We examined 1) contractile properties and the intracellular Ca(2+) concentration ([Ca(2+)](i)) transient in cardiac myocytes and 2) sarcoplasmic reticulum (SR) Ca(2+) uptake and release function in myocardium from patients with end-stage heart failure caused by ischemic (ICM) vs. idiopathic dilated cardiomyopathy (DCM). The amplitude of cell motion was decreased 43 +/- 6% in ICM and 68 +/- 7% in DCM compared with that in normal organ donors (DN). Time to peak of shortening was increased 43 +/- 15% in DCM, but not in ICM. Prolongation of the relaxation time was more predominant in ICM. In DCM the systolic [Ca(2+)](i) was decreased 27 +/- 9% and diastolic [Ca(2+)](i) was increased 36 +/- 11%. In ICM the diastolic [Ca(2+)](i) was increased 59 +/- 12% but the systolic [Ca(2+)](i) was unchanged. A significant decrease of the ATP-dependent SR Ca(2+) uptake rate associated with the reduction of the SR Ca(2+)-ATPase protein level was found in ICM. In contrast, the significant decrease in SR Ca(2+) release rate was distinct in DCM. The large amount of Ca(2+) retained in the SR associated with a significant decrease in the maximum reaction velocity and increase in the Michaelis-Menten constant in the caffeine concentration-response curve suggests a fundamental abnormality in the SR Ca(2+) release channel gating property in DCM. We conclude that potentially important differences exist in the intracellular Ca(2+) homeostasis and excitation-contraction coupling in ICM vs. DCM. The SR Ca(2+) release dysfunction may play an important pathogenetic role in the abnormal Ca(2+) homeostasis in DCM, and the SR Ca(2+) uptake dysfunction may be responsible for the contractile dysfunction in ICM.

Atrial conduction disturbance as an indicator of rejection after cardiac transplantation

BACKGROUND

Abnormalities of the terminal force of the P wave in Lead V1 (ptf-V1) and dispersion of corrected atrial repolarization (Ta-TcD) are believed to represent interatrial conduction defect.

METHODS AND RESULTS

To determine whether atrial conduction disturbance correlates with cardiac allograft rejection, we analyzed 249 twelve-lead-electrocardiograms, echocardiograms, hemodynamic parameters, and endomyocardial biopsys from 137 patients with heart transplantation. Both ptf-V1 and Ta-TcD were significantly increased in patients with severe, moderate, and mild rejection. In 22 patients, significant increases of the ptf-V1 and Ta-TcD were observed before positive histological findings, and significantly correlated with severity of rejection during 5- week to 1-year follow-up. Increase of 0.030 mm x sec in ptf-V1 or 0.040 s1/2 in Ta-TcD indicated cardiac rejection > or =1B with sensitivity of 88 and 83%, specificity of 85 and 77%, respectively.

CONCLUSION

These results suggest that the ptf-V1 and Ta-TcD might be an adjunct to detect rejection and reduce the number of surveillance EMB.

[Early arthroscopic reconstruction in treatment of acute complete rupture of anterior cruciate ligament]

OBJECTIVE

To early reconstruct acute and complete rupture of anterior cruciate ligament (ACL) and treat combined injuries for the recovery of knee joint stability.

METHODS

Ten cases of acute complete rupture of anterior cruciate ligament and medial collateral ligament were treated arthroscopically by anterior cruciate ligament reconstruction using patellar tendon autograft fixed with interference screw from February 1998 to March 1999.

RESULTS

Follow-up ranged from 5 months to 1 year and 3 months (average 10 months). Clinical results showed that the stability of knee joint was satisfactory in the early stage.

CONCLUSIONS

Acute the ACL rupture can be reconstructed arthroscopically in the early stage and the injuries were moderate, combined injuries could be treated at the same time, and the stability of knee joint could recover in the early stage after operation.

A disposable amperometric sensor screen printed on a nitrocellulose strip: a glucose biosensor employing lead oxide as an interference-removing agent

A new type of disposable amperometric sensor is devised by screen printing thick-film electrodes directly on a porous nitrocellulose (NC) strip. The chromatographic NC strip is then utilized to introduce various sample pretreatment layers. As a preliminary application, a glucose biosensor based on hydrogen peroxide detection is constructed by immobilizing glucose oxidase (GOx) on the NC electrode strip and by formulating a strong oxidation layer (i.e., PbO2) at the sample loading area, placed below the GOx reaction band. The screen-printed PbO2 paste serves as a sample pretreatment layer that removes interference by its strong oxidizing ability. Samples applied are carried chromatographically, via the PbO2 paste, to the GOx layer, and glucose is catalyzed to liberate hydrogen peroxide, which is then detected at the electrode surface. The proposed NC/PbO2 strip sensor is shown to be virtually insusceptible to interfering species such as acetaminophen and ascorbic and uric acids and to exhibit good performance, in terms of the sensor-to-sensor reproducibility (standard deviation, +/-0.026 - +/-0.086 microA), the sensitivity (slope, -0.183 microA/mM), and the linearity (correlation coefficient, 0.994 in the range of 0-10 mM).

Spontaneous ECLomas in cotton rats (Sigmodon hispidus): tumours occurring in hypoacidic/hypergastrinaemic animals with normal parietal cells

We have identified cotton rats with a high female-predominant occurrence of spontaneous gastric carcinomas localized to the oxyntic mucosa, classified as malignant enterochromaffin-like (ECL) omas. The present study was made to further characterize these ECLomas and surrounding oxyntic mucosa, both morphologically using histochemical and immunohistochemical methods, and for gene expression by northern blot analysis. Among eight female cotton rats, three had an irregularly thickened oxyntic mucosa, increased stomach weight and a high serum gastrin level. Histopathological examination showed adenomatous hyperplasia of the thickened oxyntic mucosa with areas of an invasive neoplastic tumour. Immunohistochemistry, using the general neuroendocrine cell marker chromogranin A (CgA) and the specific ECL cell marker histidine decarboxylase (HDC), showed a considerably increased ECL cell density. These ECL cells displayed active proliferation, with hyperplasia, dysplasia and neoplasia. Parietal cells were not found in the tumour tissue. Parietal cell density was only slightly reduced in the surrounding oxyntic mucosa. The antral mucosa was histopathologically normal with a normal number of gastrin-immunoreactive cells. Likewise, somatostatin-immunoreactive cells did not show any differences in the antral and oxyntic mucosa between rats with pathological and normal oxyntic mucosa. Northern blot analysis revealed increased expression of CgA and HDC mRNA in the thickened oxyntic mucosa, whereas H(+)/K(+) ATPase mRNA was similar in the oxyntic mucosa of those with thickened and normal oxyntic mucosa. Gastrin mRNA in the antral mucosa was high in animals with thickened oxyntic mucosa. Somatostatin mRNA expression was similar in the antral mucosa of control animals and animals with a thickened oxyntic mucosa. We conclude that the spontaneous gastric carcinoma occurring in female cotton rats is an ECLoma developing secondary to hypergastrinaemia due to reduced intragastric pH. The mechanism for reduced acidity is not known, but is not gastric atrophy.

[Acute rupture of anterior cruciate ligament: diagnosis and treatment by early arthroscopy]

OBJECTIVE

To early diagnose and treat acute rupture of anterior cruciate ligament (ACL).

METHODS

23 patients with acute rupture of ACL were examined and treated by early arthroscopy.

RESULTS

The preoperative diagnosis of ACL rupture was similar to that of in 18 patients. Three patients were confirmed by early arthroscopy and 2 patients were found to have ACL rupture, 16 patients were combined with meniscus injuries and 6 patients with cartilaginous injuries. Patholanatomical type of ACL were rupture of parenchymal part (21 patients) and avulsion rupture of attachment point (2 patients). In 6 patients ACL was reconstructed under arthroscope.

CONCLUSIONS

Early arthroscopy in the treatment of acute ACL rupture has advantages of minor injury, correct diagnosis, visible location of injury or combined injury and timely treatment. Early arthroscopy for acute ACL rupture is an important measure for diagnosis, treatment, and stabilization of the knee joint.

[Evaluation of the histologic criteria for the diagnosis of Sjögren's syndrome]

OBJECTIVE

The most important diagnostic criterion in Sjögren's syndrome (SS) is considered to be the histologic focus score of the labial salivary glands. The focus score is defined as the number of lymphocytic foci per 4 mm2 of the salivary gland according to the criterion of Chisholm & Mason. On the other hand, in the criteria of the Sjögren's Disease Research Committee of the Ministry of Health and Welfare in Japan it is defined as the number of lymphocytic foci per a lobule of the salivary gland. By setting the limited criteria for SS on the basis of objective signs of both dry eyes and dry mouth, we compared the usefulness of these two diagnostic criteria for the diagnosis of SS in terms of the sensitivity, the specificity and laboratory data.

METHODS

The biopsy of labial salivary glands was performed in 245 patients (230 females and 15 males, with a mean age of 54.9 years) who were suspected of SS in our hospital during the time between 1975 and 1996. Labial salivary glands were histologically assessed and the focus score was calculated according to the criterion of Chisholm & Mason and to that of the Sjögren's Disease Research Committee, respectively.

RESULTS

The average area per a lobule of the salivary gland was 0.70 mm2. According to the limited criteria for SS, the Japanese histologic diagnostic criteria showed a higher specificity (93.3%) and a lower sensitivity (23.5%). The sensitivity of the criterion of Chisholm & Mason was 72.1%, and the specificity was 80.0%. The margin of the lobule was sometimes difficult to be identified because of the fatty change and fibrosis in some salivary glands.

CONCLUSIONS

By comparing the two different histologic criteria using our limited criteria, it was better to use the histologic criterion of Chisholm & Mason as a criterion for the diagnosis of SS than that of the Sjogren's Disease Research Committee of the Ministry of Health and Welfare in Japan in terms of the sensitivity, the specificity and laboratory data.

Different Effects of Amiodarone and Quinidine on the Homogeneity of Myocardial Refractoriness in Patients With Intraventricular Conduction Delay

BACKGROUND: Increases in QT and JT dispersion have been suggested as indicative of a proarrhythmic potential as a result of heterogeneity in myocardial refractoriness, the reduction of which by antiarrhythmic agents might be associated with a beneficial effect on the development of serious ventricular arrhythmias. METHODS: To test the hypothesis that amiodarone reduces the heter-ogeneity of ventricular refractoriness to a significantly greater extent than quinidine in patients with intraventricular conduction defects under treatment for ventricular arrhythmias, the corrected and uncorrected QT and JT intervals and dispersions from 12-lead surface electrocardiograms were determined in 120 patients with intraventricular conduction defects with cardiac arrhythmias before and during treatment with amiodarone (n = 60) and quinidine (n = 60). RESULTS: Amiodarone increased QT from 403 +/- 50 ms to 459 +/- 47 ms (P <.001), with a similar increase in the corrected QT interval (QTc) (P <.001). Amiodarone reduced QT dispersion by 40% (P <.001), whereas quinidine increased by 18% (P <.001). The net effects of both drugs were similar for OTc. Amiodarone, but not quinidine, reduced heart rate significantly; amiodarone had no effect on the QRS; but quinidine increased if (P <.001). Quinidine as well as amiodarone increased the JT and JTc intervals significantly, but the effect of quinidine was qualitatively less striking. Amiodarone decreased the JT dispersion by 33% (P <.001) and JTc dispersion by 37% (P <.001). On the other hand, quinidine increased the corresponding values for JT and JTc by 18% (P <.001) and 21% (P <.001), respectively. The overall data on QT and JT dispersion indicate an improvement in the homogeneity of myocardial refractoriness with amiodarone treatment and the converse with quinidine treatment; this observation is consistent with a lower proarrhythmic propensity and mortality with amiodarone than with quinidine. Quinidine increased the QRS interval more than amiodarone, and the data indicate that in patients with intraventricular conduction defects, the monitoring of the JT interval might more accurately reflect changes in myocardial repolarization. CONCLUSIONS: Amiodarone and quinidine both increased the corrected and uncorrected QT and JT intervals; amiodarone decreased and quinidine increased the dispersion of these intervals, and these results suggested an improvement in the homogeneity of myocardial refractoriness as a result of amiodarone treatment and the converse as a result of quinidine treatment. Quinidine increased the QTS interval more than amiodarone, and the data indicate that in patients with intraventricular conduction defects, the monitoring of the JT interval might more accurately reflect changes in myocardial repolarization.

Electrophysiological effects of MS-551, a new class III agent: comparison with dl-sotalol in dogs

MS-551 is a newly synthesized, nonspecific K+ channel blocker. To elucidate its electrophysiological and potential proarrhythmic effects relative to those of dl-sotalol in vivo, serial changes in ECGs, endocardial and epicardial monophasic action potential durations, and left and right ventricular pressures were measured simultaneously in pentobarbital-anesthetized open-chest dogs. Complete heart block was produced by the injection of 37% formaldehyde into the atrioventricular node. Intravenous administration of MS-551 produced prolongation of action potential duration at 90% repolarization time (APD90) immediately after the beginning of infusion and reached plateau at 10 min. MS-551 (1 mg/kg) caused 73 +/- 8% increase in APD90 and 28 +/- 5% increase in QTc at basic cycle length of 700 msec. The maximal prolongation of APD90 induced by 1 mg/kg MS-551 was 39% greater than that by the same dose of sotalol (P < .01). The dose-response curve of prolongation of ventricular effective refractory period produced by MS-551 was shifted significantly to the left compared with that induced by sotalol. The EC50 was 0.5 +/- 0.1 mg/kg and 1.2 +/- 0.2 mg/kg for MS-551 and sotalol, respectively (P < .05). When 0.5 mg/kg MS-551 doses were used, no ventricular arrhythmia was induced by stimulation at 200-msec basic cycle length. When 1.5 mg/kg sotalol was administered, 5 of 15 developed torsade de pointes, 2 of 15 developed ventricular fibrillation and 5 of 15 developed sustained ventricular tachycardia. The idioventricular rates and left ventricular pressures were reduced significantly by sotalol, not by MS-551. In conclusion, MS-551 is a potent class III antiarrhythmic agent that selectively prolongs repolarization in the ventricular myocardium and appears to be devoid of autonomic effects. Dose for dose, it is more potent in prolonging the APD90 and the right ventricular effective refractory period possibly with a lower tendency for the development of proarrhythmia in a canine heart-block model.

[An application of genetic algorithms to the analysis of EXAFS spectrum]

Extended X-ray absorption fine structure (EXAFS) has been extensively used in the structural study in recent years. But the current methods of analysis EXAFS spectrum is difficult and tedious,demanding either very similar standard samples or the initial parameters near the solution. In this paper, a new technique Genetic Algorithms (GAs), was applied to the analyzing of the EXAFS spectrum,and two spectra of CU samples were investigated by the method. It was found that reasonable results can be obtained by the method only with limiting the initial parameters to a broad range. Comparing the results with those obtained by EXCURVE88, the fitting is superior, and the parameters are reasonable. Therefore, it is proved that the GAs may be a high performance method for the analyzing of the EXAFS spectra.

[Long-term follow-up of 43 patients with Sjögren's syndrome]

OBJECTIVE

To study the long-term outcome in patients with Sjögren's syndrome (SS).

METHODS

We retrospectively studied a cohort of 43 patients with SS; 31 patients with primary SS and 12 patients with secondary SS (6 patients with rheumatoid arthritis, 3 patients with mixed connective tissue disease, 2 patients with systemic lupus erythematosus and 1 patient with systemic sclerosis). Follow-up assessments were performed for 10-20 years following the initial diagnosis.

RESULTS

During follow-up, 29 patients (67%) with SS developed new extraglandular manifestations including: a small amount of monoclonal gammopathy (10 patients), interstitial pulmonary disease (8 patients), malignancy (4 patients developed cancer, 1 patient developed malignant lymphoma), Raynaud's phenomenon (4 patient), peripheral neuropathy (3 patients), renal disease (2 patients), myopathy (2 patients) and others. Statistically significant differences in the salivary gland scintigraphy existed between the progressed group and the stable group at both the initial diagnosis and ten years later. Patients with anti-Ro (SS-A) antibody had a high incidence of salivary gland enlargement, hypocomplementemia, rheumatoid factor and anti-nuclear antibody. The focus scores of the labial salivary biopsy in anti-La (SS-B) antibody positive patients were significantly higher than in patients without this antibody. No statistically significant differences were noted in symptoms and signs between study entry and follow-up.

CONCLUSIONS

Although sicca symptoms involving the eyes and the mouth did not progress in most of SS patients, 67.4% of SS patients developed new extraglandular manifestations during the 10-20 years follow-up period.

Study of simplified measures for malaria surveillance in the late consolidation phase in China

This paper presents the results of a study on simplified surveillance methods conducted in 23 pilot counties in 11 provinces and municipalities in China where reside 15 million people and malaria control has been in the late consolidation phase. Two simplified surveillance Schemes (A and B) taking treatment of clinical cases as the main measure were implemented in 1992-1994. The rate of annual blood examination for case detection was 1.0% in pilot Scheme A, while in areas of scheme B it was 0.3%. The implementation of both Scheme A and Scheme B, simplified or without treatment of infection foci and management of mobile populations, acquired satisfactory effects against malaria. Consequently, malaria incidence was declining steadily, only a few indigenous and introduced cases were detected. The parasite rate in residents and the IFA positive rate in children were very low. The results of pilot studies and cost-effectiveness analysis indicated that Scheme B is effective, rational and economic, and can be implemented to replace the routine surveillance measures in areas where malaria has been at the late consolidation phase in China.

Acute effects of thyroid hormone on inward rectifier potassium channel currents in guinea pig ventricular myocytes

Thyroid hormones play an important role in cardiac electrophysiology. However, the regulation of cardiac ionic channels by thyroid hormones is still unclear. To evaluate the acute effect of 3,3',5-triiode-L-thyronine (T3) on inward rectifier potassium channel (IK1) action potentials, whole-cell IK1 currents and steady-state single IK1 currents were recorded in guinea pig ventricular myocytes. Acute exposure of cells to T3 resulted in shortening of the action potential durations. This effect was initiated at 5-15 min and reached a stable plateau at 25 min. The amplitude of steady-state whole-cell IK1 was significantly increased by T3 at 1 nM to 1 microM concentration rage and with ED50 12 nM/liter. T3 (1 microM) increased IK1 by 68 +/- 7% at -40 mV and 52 +/- 9% at -100 mV. Similar effects were observed with triiodothyroacetic acid, an analogue of T3 that does not stimulate DNA transcription. The single IK1 open probability (Po) was increased 7 +/- 1% by 1 nM T3 (n = 9, P < 0.05) and 42 +/- 6% by 1 microM T3 at -40 mV (n = 18, P < 0.0001). However, the channel unit amplitude, time constants of open and fast-closed time were not changed. T3 shortened interburst duration at each membrane potential but did not change the burst behavior. To elucidate detailed mechanism, we assumed a three-state model (C1 <==> C2 <==> O) and calculated each rate constant. T3 significantly increased the rate constant, k+1, for the transition from the C1 to the C2 state at RP -40 mV (2.84 +/- 0.56 to 7.28 +/- 1.23 sec-1, P < 0.01), RP -20 mV (3.63 +/- 0.95 to 10.17 +/- 2.60 sec-1, P < 0.05) and RP (6.73 +/- 1.20 to 21.94 +/- 4.49 sec-1, P < 0.01). However, the other rate constants were not affected. These results demonstrate that T3 enhances IK1 with the increment in Po, which mainly results from shortening of interburst duration without any changes in burst behavior. Hence, the shortening of interburst duration is due to acceleration of the transition from the C1 to the C2 state. The enhanced IK1 by T3 might be one of the causes for shortened action potential duration in hyperthyroidism.

Effects of amiodarone, sematilide, and sotalol on QT dispersion

To study the effects of class III agents on QT/QTc dispersion in patients with heart disease and cardiac arrhythmias, QT dispersion and QRS and RR intervals were compared in patients before and after treatment with amiodarone (n = 26), sematilide (n = 26), and sotalol (n = 26). QT, QRS, and RR intervals, and QTc values were calculated for each complex, and their mean values were calculated for each lead. QT and QTc dispersions were defined as differences between the minimal and maximal QT or QTc values in each of the 12 leads studied. Amiodarone, sematilide, and sotalol all significantly prolonged the QT interval and the QTc value. Significant reductions in QT and QTc dispersions were only found in the amiodarone group (QT dispersions: 79 +/- 13 vs 49 +/- 14 ms; p < 0.001; QTc dispersions: 0.08 +/- 0.02 vs 0.05 +/- 0.01 s1/2; p < 0.001). The mean RR interval was significantly increased in patients after treatment with amiodarone (p < 0.001) and sotalol (p < 0.001), but not in patients receiving sematilide treatment (p > 0.2). The baseline QT and QTc dispersions were significantly greater in patients with than without myocardial infarction before treatment (p < 0.001). The mean baseline values for QT/QTc dispersions were not significantly different among all 3 groups. However, only amiodarone significantly reduced the QT dispersion (from 76 +/- 10 to 46 +/- 11 ms; p < 0.001) and QTc dispersion (from 0.09 +/- 0.02 to 0.05 +/- 0.01 s1/2; p < 0.001) in patients with myocardial infarction.(ABSTRACT TRUNCATED AT 250 WORDS)

Persistence and extinction of a population in a polluted environment

Models of the persistence and extinction of a population or community in a polluted environment have been investigated in several papers. But all of those papers have a basic assumption that the capacity of the environment is so large that the change of toxicants in the environment that comes from uptake and egestion by the organisms can be neglected. This assumption is not made in this article. Some sufficient conditions on persistence or extinction of a population have been obtained, and the threshold between the two has also been obtained for most situations.